A machine stacks boxes. In the first minute, it stacks 15 boxes, but in the next minute, 5 boxes fall down. If the machine stacks in alternate minutes, how many minutes will it take to stack a total of 95 boxes?
Show answer & explanation
Correct answer: B
Explanation
Number of boxes placed in 2 minutes = 15 − 5 = 10 boxes
8 such cycles in 16 minutes –
8 × 10 = 80 boxes
Machine in the 17th minute = 80 + 15 = 95
Time taken to place 95 boxes = 17 minutes