A technology company determined that an average of 3 phones were defective for every 200 phones it produced. At this rate, about how many phones were defective if the company produced 50,000 phones?

You have to calculate the probability for the given average:

= 3/200 = 0.015 = 1.5%

For 50,000 phones you have to multiply the probability by 50,000:

0.015*50,000 = 750 phone defectives if the company produced 50,000