The sum of three numbers is 98. If the ratio of the first to the second is 2 : 3 and that of the second to the third is 5 : 8, then the second number is?

A. 20
B. 30
C. 48
D. 58

Answer

Correct Answer: B. 30 


Solution

Let the three parts be A, B, C Then,
A : B = 2 : 3 and B : C = 5 : 8 (5 X 3/5 ) : (8 X 3/5 ) = 3 : 24/5
A:B:C= 2 : 3 : 24/5 10:15:24
B = (98 X 15/49 ) = 30.

The number of seats available for Biology and Computer Science in a school is in the ratio 5:8. They are to be increased by 30% and 25% . Find the new ratio.

A. 6:10
B. 13:20
C. 3:4
D. 35:33

Answer

Correct Answer: B. 13:20 


Solution

Let the number of seats be 5x and 8x. New ratio
= (1.3*5x):(1.25*8x)
= 6.5x:10x
= 13:20

The sum of three numbers is 172. The ratio of the first and second numbers is 8:11. The ratio of the second and third is 5:7. Find the second number.

A. 44
B. 55
C. 66
D. 77

Answer

Correct Answer: B. 55 


Solution

Let the numbers be a, b and c. a+b+c = 172 a:b = 8:11 b:c = 5:7 11a = 8b a = 8b/11 7b = 5c c = 7b/5 (8b/11)+b+(7b/5) = 172 40b+55b+77b = 172*55 172b = 172*55 b=55

If a flat costs Rs.4500 per sq. ft, and a commercial space costs Rs.9500 per sq. ft, then what is the ratio of their areas if the total cost of both are the same?

A. 9:19
B. 19:9
C. 15:28
D. 28:15

Answer

Correct Answer: B. 19:9 


Solution

Let A1 be the area of flat and A2 be that of the commercial space
Total cost = area * rate
Therefore, cost of flat = A1*4500 ; cost of commercial space = A2*9500
Both the above costs are same
A1*4500 = A2*9500
A1:A2 = 9500:4500 = 19:9

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