# Number of days the project delayed

**Problem**

A contractor estimates that he could finish a project in 15 days if he has 20 men. At the start, he hired 10 men then after 6 days, 10 more men are added. How many days was the project delayed?

A. 5 | C. 6 |

B. 3 | D. 4 |

**Answer Key**

[ B ]

**Solution**

$\text{Work load } ~ = 20(15) = 300 ~ \text{ man-days}$

$10(6) + 20x = 300$

$x = 12 ~ \text{ days}$

$\text{Actual duration } = 6 + x = 18 ~ \text{ days}$

The project was delayed by 3 days.