6
Q:

The difference between a positive proper fraction and its reciprocal is 9 / 20. Then the fraction is :

 A) 3/5 B) 3/10 C) 4/5 D) 5/4

Explanation:

Let the required fraction be x. Then, (1 / x )- x = 9/20
1 - x^(2) / x = 9 / 20  =>  20 - 20 * x^(2) = 9 * x.
20 * x^(2) + 9 *x - 20 = 0.
=> (4 * x + 5) (5 * x - 4) = 0.
=> x = 4 / 5.

Q:

Find the next number in the series 125, 80, 45, 20, ....

 A) 5 B) 15 C) -5 D) 10

Explanation:

The pattern is -45, -35, -25, -15

The next number = 20-15= 5

7 45
Q:

Find the next number in the series 141,137,146,130,155,119,...

 A) 147 B) 168 C) 162 D) 182

Explanation:

The pattern is -4, +9,-16, +25, -36

The next number=119+49=168

4 14
Q:

Find the next number in the series 3, 4, 5, 5, 12, 13, 7, 24, 25, 8, 15, ...

 A) 26 B) 16 C) 17 D) 18

Explanation:

The pattern is $3^{2}+4^{2}=5^{2}$,  $5^{2}+12^{2}=13^{2}$$7^{2}+24^{2}=25^{2}$

The next number = $8^{2}+15^{2}=17^{2}$

i.e. 17

9 143
Q:

Find the next number in the series 14, 916, 2536,......

 A) 4981 B) 6481 C) 4964 D) 6449

Explanation:

The pattern is $1^{2}$$2^{2}$$3^{^{2}}$$4^{2}$$5^{2}$$6^{2}$

The next number= $7^{2}^{}$$8^{2}$ = 4964

10 163
Q:

Find the next number in the series 2, 3, 4, 8, 9, 10, 11, 16, 17, 18, 19, 20,...

 A) 27 B) 26 C) 24 D) 25