How many MP3 players in the shipment would you predict to be damaged if 6 MP3s in the sample had been damaged

Given that there is a little information I would say all is damaged.

Substitute values into the proportion.

Substitute known values. Let x be the number of defective MP3 players in the population.

6 / 50 = x / 3500

50 x 70 = 3500, so multiply the numerator and denominator of the fraction 6/50 by 70.

(6x70) / (50x70) = x / 3500

420 / 3500 = x / 3500

420 = x

Based on the sample, we can predict that 420 MP3 players in the shipment would be defective.