# Determining the probability using binomial distribution.

The Bell telephone co. surveyed an apartment building with 500 units to find out who subscribes to their service. Turns out 70% of the units use Bell's service.

Find the probability that less than 340 units are using Bell services so we are looking for:

P(X<340)

Z= 340-350/10.25=-0.98

#### Solution Preview

...oblem is: P(Z<-0.9756)

And because Z is normal probability, it is symmetrical on both sides of zero. Then: ...