Question

Fill In The Blanks

In Q.No. 5, the probability that a bulb selected at random from the the lot has life less than 900 hours is _________.

Answer 1

Number of bulbs in the lot = 80

Number of bulbs having life time less than 900 hours

= Number of bulbs having life time 300 hours + Number of bulbs having life time 500 hours + Number of bulbs having life time 700 hours

= 10 + 12 + 23

= 45

∴ P(Bulb selected at random has life time less than 900 hours)

= $\frac{\mathrm{Number}\mathrm{of}\mathrm{bulbs}\mathrm{having}\mathrm{life}\mathrm{time}\mathrm{less}\mathrm{than}900\mathrm{hours}}{\mathrm{Number}\mathrm{of}\mathrm{bulbs}\mathrm{in}\mathrm{the}\mathrm{lot}}$

= $\frac{45}{80}$

= $\frac{9}{16}$

Thus, the probability that a bulb selected at random from the lot has life time less than 900 hours is $\frac{9}{16}$.

The probability that a bulb selected at random from the the lot has life less than 900 hours is $\underline{\frac{9}{16}}$.