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.