Quantitative Aptitude - Arithmetic Ability Questions

Let B's present age = x years. Then, A's present age = (x + 9) years.
(x + 9) + 10 = 2(x - 10)

 => x + 19 = 2x - 20

 => x =39.

The given number series follows a pattern that

196, 169, 144, 121, 100, 81, ?

    -27  -25   -23   -21  -19  -17

=> 81 - 17 = 64

Therefore, the series is 196, 169, 144, 121, 100, 81, 64.

The given series of numbers follow the rule that,

2880/6 = 480
480/5   = 96
96/4     = 24
24/3     = 8
8/2       = 4
4/1       = 4

But 92 is not in the rule. It is the wrong number in the given series.

Here the given number series  3, 10.5, 36.75, 128.625, ? follows a pattern that

3

3 x 3.5 = 10.5

10.5 x 3.5 = 36.75

36.75 x 3.5 = 128.625

128.625 x 3.5 = 450.187

Hence the next number in the given number series is 450.187.

Let original length = x metres and original breadth = y metres.

Original area = xy sq.m 

Increased length  = 120100 and Increased breadth = 120100 

New area = 120100x*120100y=3625xy m2 

The difference between the Original area  and New area  is:  

3625xy-xy

1125xy Increase % =1125xyxy*100= 44%

Speed =   6005×60 m/sec= 2 m/sec = 2 x (18/5) km/hr = 7.2 km/hr

Let the numbers 13a and 13b.

Then, 13a x 13b = 2028

=>ab = 12.

Now, the co-primes with product 12 are (1, 12) and (3, 4).

[Note: Two integers a and b are said to be coprime or relatively prime if they have no common positive factor other than 1 or, equivalently, if their greatest common divisor is 1 ]

So, the required numbers are (13 x 1, 13 x 12) and (13 x 3, 13 x 4).

Clearly, there are 2 such pairs.