Question

A software company sets up m number of computer systems to finish an assignment in 17 days. If 4 computer systems crashed on the start of the second day, 4 more computer systems crashed on the start of the third day and so on, then it took 8 more days to finish the assignment. The value of m is equal to :

• A. 125
• B. 150
• C. 180
• D. 160

Answer 1

Answer: (B)

150

Answer 2

$17m = m + (m - 4) + (m - 4 \times 2) + \dots + (m - 4 \times 24)$

$17m = 25m - 4(1 + 2 + \dots + 24)$

$8m = 4 \times \frac{24 \times 25}{2} = 150$