Answer:
0.45
Step-by-step explanation:
Probability of bad motherboard(MB) = 0.30
Probability of bad hard-drive(H) = 0.40
Probability of bad motherboard and hard-drive (MB and H) = 0.15
P(MB U H)= P(MB) + P(H) -P(MB and H)
=0.30+0.40-0.15=0.55
Probability that a 5 year old computer would have no problems of motherboard and hard-drive =
1-P(MB U H) = 1-0.55= 0.45