Question

$20$,$20$,$19$,$16$,$17$,$13$,$14$,$11$,$?$,$?$.

• A. a) $15$,$18$
• B. b) $10$,$10$
• C. c) $12$,$14$
• D. d) $13$,$16$

Answer 1

The correct option is B

b) $10$,$10$

Explanation for correct option :

There are two sequences in the given sequence,

The numbers in odd places follow one sequence and the numbers in even places follow another sequence.

Let's take the numbers in odd places and even places separately.

The numbers in odd places are $20$, $19$, $17$, $14$, $?$

In this sequence, we are subtracting the first four natural numbers to get the next numbers in the following manner i.e,

$20$ $-$$1$ $=$$19$

$19$ $-$$2$ $=$$17$

$17$ $-$$3$ $=$$14$

and so next number will be

$14$ $-$$4$ $=$$10$

Therefore, the question mark is replaced by $10$ .

The numbers in even places are $20$, $16$, $13$, $11$, $?$

In this sequence, we are subtracting the first four natural numbers in reverse order such as $4$,$3$,$2$,$1$ respectively to get the next numbers in the following manner i.e,

$20$ $-$$4$ $=$$16$

$16$ $-$$3$ $=$$13$

$13$ $-$$2$ $=$$11$

and so the next number is

$11$ $-$$1$ $=$$10$

Therefore, the question mark is replaced by $10$ .

Hence, the answer for given question is $10$, $10$.