Logic & Reasoning

Look at this series: 4, 7, 25, 10, __, 20, 16, 19,… What number should fill the blank?

a. 13
b. 15
c. 20
d. 28
  1. a. 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.

Test ID: 572
Source: 501 challenging logic & reasoning problems