Mathematics Quiz For RRB NTPC : 7th December

| Updated On December 14th, 2019 at 04:36 pm

Q1. The selling price of 10 oranges is the cost price of 13 oranges. then the profit percentage is :
(a) 30%
(b) 10%
(c) 13%
(d) 3%

Q1. Ans. (a)
Sol.
Profit percentage = (13-10)×100/10 = 30%

Q2. A circle of radius 8 cm has its radius decreased by 2 cm. What is the approximate percentage decrease in the area?
(a) 25%
(b) 50%
(c) 38%
(d) 43.75%

Q2. Ans. (b)
Sol.
Original area of the circle = π (8)2 = 64 π
New area of the circle = π (6)2 = 36 π
% decrease in area = 64 π – 36 π / 64 π x 100 = 43.75%

Q3. The sum of three consecutive odd numbers is 20 more than the smallest number. What is the middle number?
(a) 7
(b) 9
(c) 11
(d) 5

Q3. Ans. (b)
Sol.
Let the numbers be x, x + 2 and x + 4. Then
x + (x + 2) + (x + 4) = x + 20
x = 7
So the middle number is 9.

Q4. A fruit seller had some apples. He sells 40% apples and still has 420 apples. Originally, he had:
(a) 600 Apples
(b) 700 Apples
(c) 500 Apples
(d) None of these

Q4. Ans. (b)
Sol.
Suppose originally he had x apples.
Then, (100 – 40)% of x = 420.
60/100 × x = 420
x = (420 x 100)/60 = 700.

Q5. Two trains 140 m and 160 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time (in seconds) which they take to cross each other, is:
(a) 10.8 sec
(b) 9.5 sec
(c) 7.4 sec
(d) 8.9 sec

Q5. Ans. (a)
Sol.
Relative speed = (60 + 40) km/hr = 100×5/18 = 250/9 m/ sec.
Distance covered in crossing each other = (140 + 160) m = 300 m.
Required time = 300×9/250 = 54/5 = 10.8 sec.

Q6. When a commodity is sold for Rs 34.80, there is a loss of 25%. What is the cost price of the commodity?
(a) 46.40
(b) 43
(c) 26.10
(d) 43.20

Q7. The two numbers are in the ratio 2:3 and their product is 54 the sum of the numbers is?
(a) 15
(b) 5
(c) 9
(d) 6

Q8. In how many years a sum of money will triple itself at 8% per annum simple interest.
(a) 25 years
(b) 37.5 years
(c) 20 years
(d) 30 years

Q9. In how much time a train of length 120 m running at 45km/hr can cross a platform of length 230 m?
(a) 36 sec
(b) 28 sec
(c) 14 sec
(d) 18 sec

Q9. Ans. (b)
Sol.
Crossing time = (120 + 230)/(45 * 5/18) = 28sec

Q10. What is 6/11 of 25% of 10% of 4400?
(a) 11
(b) 66
(c) 60
(d) 36

Q10. Ans. (c)
Sol.
6/11 of 25% of 10% 4400 = 6/11 * 25/100 * 10/100 * 4400 = 60

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