CAT Questions

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Here in the given series, it follows a pattern that

77 + 2 = 79

79  - 3 = 76

76 + 5 = 81

81 -  7 = 74

74 + 11 = 85

Consecutive adding and subtracting of prime numbers.

So the wrong number in the given series is 75.

Here the given number series 625, 625, 600, ?, 475, 875 follows a pattern that

625

625 + (0 x 0) = 625

625 - (5 x 5) = 625 - 25 = 600

600 + (10 x 10) = 600 + 100 = 700

700 - (15 x 15) = 700 - 225 = 475

475 + (20 x 20) = 475 + 400 = 875

Hence, the missing number in the given number series is 700.

The working principle of a washing machine is centrifugation.

Centrifugation is a separation process which uses the action of centrifugal force to promote accelerated settling of particles in a solid-liquid mixture.

The washing machine consists of centrifuge for this purpose. A centrifuge is a piece of equipment that puts an object in rotation around a fixed axis, applying a force perpendicular to the axis of spin that can be very strong.

A's 5 days work = 50%  

B's 5 days work = 33.33% 

C's 2 days work = 16.66%     [100- (50+33.33)] 

Ratio of contribution of work of A, B and C = 50 : 3313 : 1623 = 3 : 2 : 1   

A's total share = Rs. 1500 

B's total share = Rs. 1000 

C's total share = Rs. 500  

A's one day's earning = Rs.300  

B's one day's earning = Rs.200  

C's one day's earning = Rs.250

The given number series is 

3, 5, 8, 15, 28, 51, ?

Here the pattern it follows is

3

3 + 2 = 5 ( add prime number less than 3 i.e, 2)

5 + 3 = 8 (3 is prime number less than 5)

8 + 7 = 15 (7 is prime number less than 8)

15 + 13 = 28 (13 is prime number less than 15)

28 + 23 = 51 (23 is prime number less than 28)

51 + 47 = 98 (47 is prime number less than 51)

Hence, the next number in the given number series is 98.

The terms of the series are products of two consecutive prime numbers i.e.

(2 x 3), (3 x 5), (5 x 7), (7 x 11),.....

So, 165 is wrong and must be replaced by (11 x 13) i.e. 143.