ML Aggarwal CBSE Solutions Class 8 Math 1st Chapter Rational Numbers Exercise 1.6
(2) Population of city = 6,63,432
No of adult males = 6,63,432/2
= 3,31716
No of adult females = 6,63,432/3
= 2,21,144
∴ No of children = 6,63,432 – (3,31,716 + 2,21,144)
= 6,62,432 – 5,52,860
= 1,10,572
(3) Total student appeared in exam = 400
No of girls appeared in exam = 130
∴ No of boys = 400 – 130
= 270
∴No of boys appeared in exam = 270 x 2/3
= 180
∴ No of boys failes in the exam = 270 – 180
= 90
(9) Total income = Rs. 40,000 per month
∴ food expanses = 40,000 x 3/8
= Rs. 15,000
∴ rest money = 40,000 – 15,000
= Rs. 25,000
LIC Premium expanses = 25000 x 1/5
= Rs. 5,000
rest money = 25,000 – 5000 = Rs. 20,000
∴ Other expanses 20,000 x 1/2 = Rs. 10,000
∴ rest money = 20,000 – 10,000 = Rs. 10,000
(12) Let, Nothers contribution = x
elder son’s contribution = x X 3/8
= 3x/8
younger son’s contribution = x X 1/2
= x/2
∴ According to question
3x/8 + x/2 + x = 60,000
Or, 3x+4x+8x/8 = 60,000
Or, 15x = 60,000 x 8
Or, x = 60000×8/15
= 32,000
Mothers contribution = Rs. 32,000
elder son’s contribution = 32,000 x 3/8
= Rs. 12,000
younger sons contribution = 32,000 x 1/2
= Rs. 16,000
(13) Total Students = 56
number of girls = x
∴ number of boys = 2x/5
∴ According to the question
x + 2x/5 = 56
Or, 5x+2x/5 = 56
Or, 7x = 56 x 5
Or, x = 56×5/7
= 40
∴ number of girls = 40
number of boys 40 x 2/5
= 16
(14) Let, total money = x
∴ donation of school = x x 1/10 = x/10
rest of money = x – x/10
= 10x-x/10
9x/10
donation of church = 1/6 x 9x/10
3x/20
rest of money = 9x/10 – 3x/20
= 18x-3x/20
15x/20
According to the question
15x/20 ÷ 3 = 50000
(15) Let, the number is = x
According to question
(x X 1/4) + (x X 1/3) = x/2 + 15
Or, x/4 + x/3 = x+30/2
Or, 3x+4x/12 = x+30/2
Or, 7x/6 = x+30
Or, 7x = 6x + 180
Or, 7x – 6x = 1800
Or, x = 180
(16) Let, the given number is = x
According to the question
(5/4 X x) – (4/5 X x) = 36
Or, 5x/4 – 4x/5 = 36
Or, 25x-16x/20 = 36
Or, 9x/20 = 36
Or, x = 36×20/9
= 80
