{"id":8014,"date":"2025-01-05T15:00:30","date_gmt":"2025-01-05T09:30:30","guid":{"rendered":"https:\/\/samacheerkalvi.guide\/?p=8014"},"modified":"2025-01-06T10:05:54","modified_gmt":"2025-01-06T04:35:54","slug":"samacheer-kalvi-8th-maths-guide-chapter-4-ex-4-1","status":"publish","type":"post","link":"https:\/\/samacheerkalvi.guide\/samacheer-kalvi-8th-maths-guide-chapter-4-ex-4-1\/","title":{"rendered":"Samacheer Kalvi 8th Maths Guide Chapter 4 Life Mathematics Ex 4.1"},"content":{"rendered":"

Tamilnadu State Board New Syllabus Samacheer Kalvi 8th Maths Guide<\/a> Pdf Chapter 4 Life Mathematics Ex 4.1 Text Book Back Questions and Answers, Notes.<\/p>\n

Tamilnadu Samacheer Kalvi 8th Maths Solutions Chapter 4 Life Mathematics Ex 4.1<\/h2>\n

Question 1.
\nFill in the blanks:
\n(i) If 30 % of x is 150, then x is _______ .
\nAnswer:
\n500
\nHint:
\nGiven 30% of x is 150
\ni.e \\(\\frac{30}{100}\\) \u00d7 x = 150
\n\"Samacheer
\n\u2234 x = 500<\/p>\n

\"Samacheer<\/p>\n

(ii) 2 minutes is _______ % to an hour.
\nAnswer:
\n3\\(\\frac{1}{3}\\)%
\nHint:
\nLet 2 min be x% of an hour
\nand 1 hr = 60mm
\nx% = \\(\\frac{2}{60} \\times 100=\\frac{200}{60}=\\frac{10}{3}=3 \\frac{1}{3}\\)
\nx = 3\\(\\frac{1}{3}\\)%<\/p>\n

(iii) If x% of x = 25, then x = _______ .
\nAnswer:
\n50
\nHint:
\nGiven that x% of x is 25
\n\u2234 \\(\\frac{x}{100}\\) \u00d7 x = 25
\n\u2234 x2<\/sup> = 25 \u00d7 100 = 2500
\n\u2234 x = \u221a2500 = 50<\/p>\n

(iv) In a school of 1400 students, there are 420 girls. The percentage of boys in the school is _______ .
\nAnswer:
\n70
\nHint:
\nGiven total number of students in school = 1400
\nNumber of girls in school = 420
\n\u2234 Number of boys in school = 1400 – 420 = 980
\n\"Samacheer
\n= \\(\\frac{980}{14}\\) = 70
\n% of boys = 70%<\/p>\n

\"Samacheer<\/p>\n

(v) 0.5252 is _______ %.
\nAnswer:
\n52.52%
\nHint:
\nGiven a number, and to express as a percentage, we need to multiply by 100
\n\u2234 to express 0.5252 as percentage, we should multiply by 100
\n\u2234 0.5252 \u00d7 100 = 52.52%<\/p>\n

percent difference Calculator<\/a> can be found by first finding the difference between the numbers, then finding the average of the numbers, and then dividing.<\/p>\n

Question 2.
\nRewrite each underlined part using percentage language.
\n(i) One half<\/span> of the cake is distributed to the children.
\nAnswer:
\n50%<\/span> of the cake is distributed to the children
\nHint:
\nOne half is nothing but \\(\\frac { 1 }{ 2 }\\)
\nas percentage, we need to multiply by 100
\n\u2234 \\(\\frac { 1 }{ 2 }\\) \u00d7 100 = 50%<\/p>\n

(ii) Aparna scored 7.5 points<\/span> out of 10 in a competition.
\nAnswer:
\nAparna scored 75%<\/span> in a competition
\nHint:
\n7.5 points out of 10 is \\(\\frac{7.5}{10}\\) = 0.75
\nFor percentage, we need to multiply by 100
\nWe get 0.75 \u00d7 100 = 75%<\/p>\n

(iii) The statue was made of pure silver<\/span>.
\nAnswer:
\nThe statue was made of 100% pure silver
\nHint:
\nPure silver means there are no other metals
\nso, 100 out of 100 parts is made of silver = \\(\\frac{100}{100}\\)
\n\u2234 to express as percentage, \\(\\frac{100}{100}\\) \u00d7 100% = 100%<\/p>\n

\"Samacheer<\/p>\n

(iv) 48 out of 50 students participated in sports.
\nAnswer:
\n96%<\/span> students participated in sports.
\nHint:
\n48 out of 50 students in fraction form is \\(\\frac{48}{50}\\)
\nAs a percentage, we need to multiply by 100
\n\"Samacheer<\/p>\n

(v) Only 2 persons out of 3 will be selected in the interview.
\nAnswer:
\nOnly 66\\(\\frac{2}{3}\\)% will be selected in the interview.
\nHint:
\n2 out of 3 in fraction form is \\(\\frac{2}{3}\\)
\nto express as percentage, we need to multiply by 100
\n\\(\\frac{2}{3} \\times 100=\\frac{200}{3}=66 \\frac{2}{3} \\%\\)<\/p>\n

To convert CGPA to Percentage<\/a>, we need to multiply CGPA by 9.5, which will give us the percentage.<\/p>\n

Question 3.
\n48 is 32% of which number?
\nAnswer:
\nLet the number required to be found be \u2018x\u2019
\nGiven that 32% of x is 48
\ni.e., \\(\\frac{32}{100}\\) \u00d7 x = 48
\n\"Samacheer
\n\u2234 x = 150<\/p>\n

Question 4.
\nWhat is 25% of 30% of 400?
\nAnswer:
\nRequired to find 25% of 30% of 400
\n\"Samacheer<\/p>\n

\"Samacheer<\/p>\n

The percentage decrease calculator<\/a> determines the change from one amount to a lesser amount in terms of percent decrease.<\/p>\n

Question 5.
\nIf a car is sold for \u20b9 2,00,000 from its original price of \u20b9 3,00,000, then find the percentage of decrease in the value of the car.
\n\"Samacheer
\nAnswer:
\noriginal price of car = \u20b9 3,00,000
\nactual selling price of car = \u20b9 2,00,000
\nDecrease in amount from original = 3,00,000 – 2,00,000 = 1,00,000
\n\"Samacheer<\/p>\n

Question 6.
\nIf the difference between 75% of a number and 60% of the same number is 82.5, then find 20% of that number.
\nAnswer:
\nGiven that 75% of number less 60% of number is 82.5
\nLet the number be \u2018x\u2019
\n\u2234 \\(\\frac{75}{100}\\) x x – \\(\\frac{60}{100}\\) x x = 82.5
\n\u2234 0.75 x – 0.60 x = 82.5
\n\u2234 0.15 x = 82.5
\n\u2234 x = \\(\\frac{82.5}{0.15}=\\frac{8250}{15}\\) = 550
\nRequired to find 20% of number ie 20% of x.
\n\"Samacheer<\/p>\n

Question 7.
\nA number when increased by 18% gives 236. Find the number.
\nAnswer:
\nLet the number be x. Given that when it is increased by 18%, we get 236.
\n\"Samacheer<\/p>\n

Question 8.
\nA number when decreased by 20% gives 80. Find the number.
\nAnswer:
\nLet the number be x. Given that when it is increased by 20% we get 80.
\n\"Samacheer
\nx = 100<\/p>\n

\"Samacheer<\/p>\n

It is important to learn to convert CGPA into percentage<\/a> because both the systems are interconnected.<\/p>\n

Question 9.
\nA number is increased by 25% and then decreased by 20%. Find the percentage change in that number.
\nAnswer:
\nMethod 1.
\nLet the number be x.
\nFirst it is increased by 25%
\n\u2234 It becomes x + \\(\\frac{25}{100}\\) \u00d7 x = \\(\\frac{125}{100}\\)
\nSecondary it is decreased by 20%
\n\\(\\frac{125 x}{100}-\\frac{20}{100} \\times \\frac{125}{100} x=\\frac{125}{100} x \\times \\frac{80}{100}=x\\)
\nNow we get back x, therefore there is no change.
\nHence percentage change in that number is 0%<\/p>\n

Method 2.
\n[to understand, let us assume that number is 100]
\nSo, first when we increase by 25%, we get
\n\"Samacheer
\nNow this 125 is decreased by 20%, we get
\n125 – \\(\\frac{25}{100}\\) \u00d7 125 = 125 – 25 = 100
\n\u2234 We get back 100 \u21d2 No change
\nHence percentage change in that number is 0%<\/p>\n

\"Samacheer<\/p>\n

Question 10.
\nThe ratio of boys and girls in a class is 5:3. If 16% of boys and 8% of girls failed in an examination, then find the percentage of passed students.
\nAnswer:
\nLet number of boys be \u2018b\u2019 and number of girls be \u2018g\u2019
\nRatio of boys and girls is given as 5:3
\nb:g = 5:3 \u21d2 \\(\\frac{b}{g}=\\frac{5}{3}\\) …… (A)
\nFailure in boys = 16% = \\(\\frac{16}{100}\\) \u00d7 b = \\(\\frac{16b}{100}\\)
\nFailure in girls = 8% = \\(\\frac{8}{100}\\) \u00d7 g = \\(\\frac{8g}{100}\\)
\nPass in boys = 100 – 16% = 84% = \\(\\frac{84}{100} b\\) …… (1)
\nPass in girls = 100 – 8% = 92% = \\(\\frac{92}{100} g\\) ……. (2)
\nFrom A, we have \\(\\frac{b}{g}=\\frac{5}{3}\\) , adding I on both sides, we get
\n\\(\\frac{b}{g}\\) + 1 = \\(\\frac{5}{3}\\) + 1
\n\\(\\frac{b+g}{g}=\\frac{5+3}{3}=\\frac{8}{3}\\)
\n\u2234 g = \\(\\frac{3}{8}\\)(b + g) ……. (3)
\nSimilarly b = \\(\\frac{5}{8}\\) (b + g) ……. (4)
\nTotal pass = pass in girls + pass in boys
\n= (1) + (2) = \\(\\frac{84}{100} b+\\frac{92}{100} g\\)
\n\"Samacheer<\/p>\n

\"Samacheer<\/p>\n

Objective Type Questions<\/p>\n

Question 11.
\n12% of 250 litre is the same as ________ of 150 litre.
\n(A) 10%
\n(B) 15%
\n(C) 20%
\n(D) 30%
\nAnswer:
\n(C) 20%
\nHint:
\n12% of 250 = \\(\\frac{12}{100}\\) \u00d7 250 = 30 lit.
\nPercentage: \\(\\frac{30}{150}\\) \u00d7 100 = 20%<\/p>\n

Question 12.
\nIf three candidates A, B and C in a school election got 153,245 and 102 votes respectively, then the percentage of votes got by the winner is ________ .
\n(A) 48%
\n(B) 49%
\n(C) 50%
\n(D) 45%
\nAnswer:
\n(B) 49%
\nHint:
\nCandidate 1: 153
\nCandidate 2: 245 – winner [as maximum votes)
\nCandidate 3: 102
\nTotal votes = 1 + 2 + 3 = 153 + 245 + 102 = 500
\n\"Samacheer
\n= \\(\\frac{245}{500}\\) \u00d7 100 = 49%<\/p>\n

\"Samacheer<\/p>\n

Question 13.
\n15% of 25% of 10000 = ________ .
\n(A) 375
\n(B) 400
\n(C) 425
\n(D) 475
\nAnswer:
\n(A) 375
\nHint:
\n15% of 25% of 10000 is
\nFirst let us do 25% of 10,000, which is
\n\"Samacheer
\nNext 15% of the above is \\(\\frac{15}{100}\\) \u00d7 2500 = 375<\/p>\n

Question 14.
\nWhen 60 is subtracted from 60% of a number to give 60, the number is
\n(A) 60
\n(B) 100
\n(C) 150
\n(D) 200
\nAnswer:
\n(D) 200
\nHint:
\nLet the number be \u2018X\u2019
\n60% of the number is \\(\\frac{60}{100}\\) \u00d7 x = \\(\\frac{60x}{100}\\)
\nGiven that when 60 is subtracted from 60%, we get 60
\ni.e \\(\\frac{60}{100}\\) x – 60 = 60
\n\u2234 \\(\\frac{60}{100}\\) x 60 + 60 = 120
\n\u2234 x = \\(\\frac{120 \\times 100}{60}\\) = 200<\/p>\n

\"Samacheer<\/p>\n

Question 15.
\nIf 48% of 48 = 64% of x, then x =
\n(A) 64
\n(B) 56
\n(C) 42
\n(D) 36
\nAnswer:
\n(D) 36
\nHint:
\nGiven that 48% of 48 = 64% of x
\n\"Samacheer
\nx = 36<\/p>\n","protected":false},"excerpt":{"rendered":"

Tamilnadu State Board New Syllabus Samacheer Kalvi 8th Maths Guide Pdf Chapter 4 Life Mathematics Ex 4.1 Text Book Back Questions and Answers, Notes. Tamilnadu Samacheer Kalvi 8th Maths Solutions Chapter 4 Life Mathematics Ex 4.1 Question 1. Fill in the blanks: (i) If 30 % of x is 150, then x is _______ . …<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false},"version":2}},"categories":[10],"tags":[],"class_list":["post-8014","post","type-post","status-publish","format-standard","hentry","category-class-8"],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/posts\/8014"}],"collection":[{"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/comments?post=8014"}],"version-history":[{"count":4,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/posts\/8014\/revisions"}],"predecessor-version":[{"id":39600,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/posts\/8014\/revisions\/39600"}],"wp:attachment":[{"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/media?parent=8014"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/categories?post=8014"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/tags?post=8014"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}