Question

A car hire firm has 2 cars which it hires out day by day. The number of demands for a car on each day is distributed as a P.D. with mean 1.5. Then the proportion of days on which the demand is refused is (e^-1.5 = 0.2231)

• A. 0.7823
• B. 0.2711
• C. 0.2717
• D. 0.2177

Answer 1

Answer: (D)

0.2177

Answer 2

λ = 1.5

X = {0, 1, 2, 3, ----- ∞ }

P(X>2) = 1-[P(X=0) + P(X=1) +P(X=2)

= 1 - (0.2231 + 1.5 x 0.2231 + $\frac { 2.25 } { 2 }$ x 0.2231)

= 1 - 0.2231 (1 + 1.5 + 1.125)

= 1 - 3.625 x 6.2231

= 1 - 0.8087

= 0.2177