Question

5% of all batteries produced are defective. Batteries are sold in packs of 4.

1)What is the probability that a pack contains exactly 2 defective batteries?

2)Atleast 1 is defective?

My working

P (def) = 0.05 P (not def) = 0.95

P (2def) = 0.05 x 0.05 = 0.0025*wrong

Alternative route > (5/100) x (4/99) = 0.00202*wrong