Computer chips are fabricated with a yield of 35% (35% are good). In a batch of 150 chips, find the probability of getting at least 60 good chips.

Answer 1

You can approximate this with a normal distribution, mean 150 x 0.35, variance 150 x 0.35 x 0.65 (so standard deviation is square root of this)

So mean is 52.5, standard deviation 5.84

Then you need p (X>60)

On a TI-84

2nd vars

normalcdf

lower = 60

upper = 1e99

mean 52.5

standard deviation 5.84

hit paste

0.0995

For the exact answer you need to sum 150 C n 0.35^n 0.65^ (150-n) for n = 60, 61, ..., 150