For every 144 light bulbs produced, 6 are defective. Find the number of defective light bulbs that could be expected out of 720.

You are going to get the rate of the detects.

6 detects : 114 light bulbs = 1/19 detects per light bulb

If there are 720 light bulbs, then the number of detects will be

720 light bulbs * 1/19 detects per light bulb = 37. 89 ≈ 38 detects