641. How much 60% of 50 is greater than 40% of 30?
A. 18
B. 13
C. 15
D. 20

Explanation:
(60/100) * 50 – (40/100) * 30
30 – 12 = 18

642. After decreasing 24% in the price of an article costs Rs.912. Find the actual cost of an article?
A. 1400
B. 1300
C. 1200
D. 1100

Explanation:
CP* (76/100) = 912
CP= 12 * 100 => CP = 1200

643. If y exceeds x by 20%, then x is less than y by_______?
A. 16%
B. 16 1/3 %
C. 16 2/3 %
D. 16 3/5 %

Explanation:
X=100 y=120
120——20
100——-? => 16 2/3%

644. What percent of 120 are 90?
A. 25%
B. 50%
C. 75%
D. 33%

Explanation:
(?% /100) * 120 = 90
? = 75%

645. Today is khadija’s birthday. After one year, she will become two times as she was ten years ago. current age of Khadija?
A. 19
B. 20
C. 21
D. 22

Explanation:
let her age be x
after 1 year her age will be x+1=2(x-10)
x+1=2x-20
1+20=2x-x
x=21 years

646. In what ratio should the profit be divided if M, N, O invests capital in ratio 2:3:5 and their timing of their investments are in the ratio 4:5:6.
A. 8:15:30
B. 5:18:28
C. 4:5:6
D. 2:3:5

Explanation:
P1:P2:P3 = (2*4):(3*5):(5*6)
= 8 : 15 : 30

647. A bag contains 50 paise, 1 rupee and 2 rupee coins in the ratio 2:5:8. If the total amount is Rs. 352, find the total number of coins in the bag.
A. 160
B. 200
C. 250
D. 240

Explanation:
Let the number of 50p, 1 rupee and 2 rupee coins be 2x,5x and 8x. 0.5*(2x)+5x+2*8x = 352 22x=352 x=16 Total no. of coins
= 2x+5x+8x
= 15x = 240

648. Three quantities X, Y and Z are such that XY=kZ where k is constant. Initially, X was at 4 and X:Y:Z was 2:3:4. If the value of Y is changed to 12 and Z is kept constant, find the value of X.
A. 2
B. 3
C. 5
D. 6

Explanation:
X:Y:Z=2:3:4
X=4
Then, Y=6, Z=8 XY=kZ 4*6=k*8 8k=24 k=3
Y=12, Z=8
X*12=3*8
X=2

649. Find the mean proportion between 5 and 45.
A. 9
B. 15
C. 25
D. 50

Explanation:
5:x::x:45 x²=45*5 = 225 x=15

650. If X:Y = 2:3, Y:Z = 4:5. Find X:Y:Z.
A. 2:3:5
B. 8:12:15
C. 2:8:5
D. 2:7:5

Explanation:
If A:B = m1:n1 ; B:C = m2:n2
Then, A:B:C = (m1*m2):(n1*m2):(n1*n2)
Therefore, X:Y:Z = (2*4):(3*4):(3*5)
= 8:12:15