Question

80 bulbs are selected at random from a lot and their lifetime is hours is recorded as under.

Lifetime (in hours)	300	500	700	900	1100
Frequency	10	12	23	25	10

One bulb is selected at random from the lot. What is the probability that its life is 1150?
(a) $\frac{1}{80}$

(b) $\frac{7}{16}$

(c) 1

(d) 0

Answer 1

(d) 0
Maximum lifetime a bulb has is 1100 hours. There is no bulb with lifetime 1150 hours.