Logic & Reasoning

Look at this series: 80, 10, 70, 15, 60, . . . What number should come next?

a. 20
b. 25
c. 30
d. 50
  1. a. This is an alternating addition and subtraction series. In the first pattern, 10 is subtracted from each number to arrive at the next. In the second, 5 is added to each number to arrive at the next.

Test ID: 531
Source: 501 challenging logic & reasoning problems