Mathematics MCQs

Two numbers are respectively 20% and 50% more than a third number. The ratio of the two numbers is :__________?

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A. 2 : 5
B. 3 : 5
C. 4 : 5
D. 6 : 7
✅ The correct answer is option C. 4 : 5.
Let the third number be x.

Then, first number = 120% of x = 120x/100 = 6x/5 second numbet = 150% of x = 150x/100 = 3x/2 Ratio of first two numbers = 6x/5 : 3x/2 =12x : 15x = 4 : 5.

A can do a certain work-in the same time in which B and C together can do it. If A and B together could do it in 10 days and C alone in 50 days, then B alone could do it in_________?

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A. 15 days
B. 20 days
C. 25 days
D. 30 days
✅ The correct answer is option C. 25 days.
(A + B)’s 1 day’s work = 1/10; C’s 1 day’s work = 1/50 (A + B + C)’s 1 day’s work = 1/10 + 1/50 = 6/50 = 3/25 Also, A’s 1 day’s work = (B + C)’s 1 day’s work

From (i) and (ii), we get : 2 x (A’s 1 day’s work) = 3/25 As 1 day’s work = 3/50 B’s 1 day’s work = 1/10 – 3/50 = 2/50 = 1/25 So, B alone could do the work in 25 days.

An automobile financier claims to be lending money at simple interest, but he includes the interest every six months for calculating the principal. If he is charging an interest of 10%, the effective rate of interest becomes :_________?

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A. 10%
B. 10.25%
C. 10.50%
D. None of these
✅ The correct answer is option B. 10.25%.
Let the sum be Rs. 100. Then, S.I. for first 6 months = Rs. ( 100 X 10 X 1/100 X 2 ) = Rs. 5. S.I. for last 6 months = Rs. ( 105 X 10 X 1/100 X 2 ) = Rs. 5.25. So, amount at the end of 1 year=Rs.(100 + 5 + 5.25) = Rs. 110.25 Effective rate = (110.25 – 100) = 10.25%.

Two taps X and Y can fill a tank in 10 hrs. and 15 hrs.respectively.  If the both taps are opened together, the tank will be full in_________?

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A. 3 hrs.
B. 4 hrs,
C. 5 hrs.
D. 6 hrs.
✅ The correct answer is option D. 6 hrs..
X’s 1 hour work = 1/10

Y’s 1 hour work = 1/15

(x+y)’s 1 hour work = 1/10+1/15=5/30=1/6

Both the taps can fill the tank in 6 hrs.