NIELIT 2016 MAR Scientist D: 52

Question

Choose the most appropriate option.

$4, 7, 25, 10, \underset{\text{_____}}{?}, 20, 16, 19$

• A. $13$
• B. $15$
• C. $20$
• D. $28$

Answer 1

Two series alternate here, with every third number following a different pattern.

In the main series, $3$ is added to each number to arrive at the next.

In the alternating series 5 is subtracted from each number to arrive at the next.

$4,7,10,13,16,19$ is one series.

$25,20$ is another series.

so missing number is $13$

Option $A$ is correct.