Solve these arithmetic sums in a jiffy
This article is in continuation to the last article focusing on the ratio and proportion topic.
1 . The weight of Mr.Gupta and Mrs. Gupta are in the ratio 7 : 8 and their total weight is 120 kg. After taking a dieting course Mr.Gupta reduces by 6 kg and the ratio between their weights changed to 5 : 6, So, Mrs. Gupta has reduced by?
a) 2 kg b) 3 kg c) 4 kg d) 5 kg
Ans: c
Solution:
Mr.Gupta : Mrs. Gupta
Before 7x : 8x
After 5y : 6y
before 7x+8x = 120 —> 15x = 120
x = 8
Mr.Gupta = 7 × 8 = 56
Mrs.Gupta = 8 × 8 = 64
After lossing 6 kg by Mr.Gupta
The ratio becomes 5 : 6
Let Mrs.Gupta loss z kg,
56-6/ 64-z = 5/6
300 = 320 – 5z
5z = 20
z = 4 kg
2. What is the mean proportional between (15+ √200 ) and (27 – √648) ?
a) b) 2 c) 3 d) 4
Ans: c
Solution : Mean proportional between a and b = √ab
= (15 +√200) (27 – √648)
= (15 x 27) – 15 x √648+
27√200 – (√200 x √648)
= 405 – 15 x 18√2+27 x 10√2 – (10 +√2 x 18√2)
= 405 – 270√ 2+270√2 – 180
x 2
= 405- 360
= 45
= 3√5
M Venkat
Director
MVK Publications
Dilsukhnagar
7671002120
