Question

An electric bulb will last $190$ days or more with a probability $0.7$ and it will last for at most $200$ days with the probability of $0.8$. The probability that the bulb will last between $190$ and $200$ days is

• A. 0.5
• B. 0.56
• C. 0.2
• D. 0.3

Answer 1

The correct option is A 0.5

$P(X\ge 190)=0.7,P(X\le 200)=0.8P(190\le X\le 200)=0.7+0.8-1=0.5$