Page 42 - Arithmetic

6. 15% of (4% of 3200) =15%of( 4 ×3200)
100
= 15% of 128
= 15 ×128=19.2
7. Three-sevenths of 35 = 3 × 35 = 15 7
Eighth-ninths of 54 = 8 × 54 = 48 9
Required percentage = 48−15 × 100 = 68.75% 48
8. B is 175% of C, then C is what percent of (B + C) B = 175C
100
100 𝐵=7
𝐶4
Add 1 on both sides 𝐵 + 1= 7 + 1
𝐶4 𝐵+𝐶 = 11
𝐶4
Required % =
𝐶 × 100 = 𝐵+𝐶
4 × 100 = 400 % or 36.36% 11 11
9. Let the original price be $x Reduced price= $ 0.80x
100 100
0.80𝑥 𝑥 100−80 = 5
-=5
0.80𝑥
20 =5 0.80𝑥
20 = 5 × 0.80x 4x =20
x = 20 = $5 4
10. Let the amount of pure milk be 100 liters
Amount of water added = 10% of 100 = 10 × 100 = 10
100
Amount of milk in the solution = 100 – 10 = 90 Amount of water added second time = 10 × 90 = 9
100
Amount of milk in the solution = 90 – 9 = 81 Amount of water added third time = 10 × 81 = 8.1
100
Amount of milk in the solution = 81 – 8.1 = 72.9
Purity of milk in the solution = 72.9 × 100 = 72.9% 100
Page 41 of 55
Arithmetic Concept