IBPS RRB Mains 2016-17 (Important Questions-2)

IBPS RRB Mains 2016-17 (Important Questions-2)

1. The area of a rectangle is 336 square centimeter. Breadth of the rectangle is four times the radius of a circle. If the perimeter of the rectangle is 80 cm, then the radius of the circle is ?

A. 5 cm
B. 4 cm
C. 3 cm
D. 2 cm
E. None of these

Sol. Lets assume the length to be 'l'
And breadth to be 'b'.

According to the question,

l*b = 336

and

2(l+b) = 80

Solving , b = 12 cm

Thus, radius of the circle = b/4 = 12/4 = 3cm.

2. Three dices are rolled simultaneously then find the probability that none of them have all same numbers ?

A. 35/36
B. 1/36
C. 5/36
D. 1/216
E. None of these

Sol. Total number of cases = 6*6*6 = 216
No. of cases where all have same numbers = 6
Number of favorable cases = (216 - 6) = 210

Thus, required probability = 210/216 = 35/36.

3. A can do a piece of work in 10 days and B can do the same work in 15 days. They work together for 3 days then B left. Find in how many days A finish the remaining work ?

A. 4 
B. 3
C. 5
D. 6
E. None of these

Sol. In 1 day working together they finish, 1/10 + 1/15 = 1/6th work.
In 3 days they will finish, = 1*3/6 = 1/2th work
Work remaining, to be done by A alone is  = 1/2th work

A finihes the whole work in = 10 days
Thus, A will finish 1/2th work in = 10/2 = 5 days.

4. An item was sold for Rss 2750. But if it was sold for 10% less, it would still made 10% profit. What is the cost price of the item ?

A. 2250
B. 2350
C. 2450
D. 2150
E. None of these

Sol. 10% 0f 2750 = Rs 275
Selling Price = 2750 - 275 = Rs 2475

Cost price = (2475*100)/(100+10) = Rs 2250.

5. In an exam, 10% boys and 10% girls passed. Number of boys is 100 and number of girls is 90. What is the percentage of candidates passed ?

A. 90
B. 80
C. 10
D. 20
E. None of these

Sol. No. of boys = 10% of 100 = 10
No. of girls = 10% of 90 = 9

Total candidates passed = 10 + 9 = 19

Percentage Failed = (1 - 19/190)*100 = 90%.

Directions (6-10): What will come in place of (_) in the following number series ?

6. 11, 13, 17, 19, 23, 29, _

A. 31
B. 37
C. 33
D. 34
E. None of these

Sol. All are prime numbers. Next prime is 31.

7. 3, 7, 15, 31, 63, _

A. 125
B. 123
C. 127
D. 129
E. None of these

Sol. 3*2 + 1 = 7
     7*2 + 1 = 15
    15*2 + 1 = 31
    31*2 + 1 = 63
    63*2 + 1 = 127.

8. 12, 36, 18, 54, 27, _

A. 81
B. 80
C. 87
D. 82
E. None of these

Sol. 12*3 = 36
     36/2 = 18
     18*3 = 54
     54/2 = 27
     27*3 = 81.

9. 9, 28, 65, 126, 217, _

A. 344
B. 354
C. 364
D. 374
E. None of these

Sol. 2^3 + 1 = 9
     3^3 + 1 = 28
     4^3 + 1 = 65
     5^3 + 1 = 126
     6^3 + 1 = 217
     7^3 + 1 = 344

10. 6, 18, 72, 360, 2160, _

A. 15120
B. 14250
C. 16540
D. 18750
E. None of these

Sol. 3*2 = 6
     6*3 = 18
    18*4 = 72
    72*5 = 360
   360*6 = 2160
  2160*7 = 15120. 

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