Abin contains 64 light bulbs of which 10 are defective. if 5 light bulbs are randomly selected from the bin with replacement, find the probability that all the bulbs selected are good ones. round to the nearest thousandth if necessary.

Astudent must have an average on five test that is greater than it equal to 80% but less than 90% to receive a final grade of b. devon's greades on the first four test were 78% 62% 91% and 80% what range if grades on the fifth test would give him a b in the course? ( assuming the highest grade is 100%)