The following table gives the life time of 400 neon lamps: Life time (in hours 300-400 400-500 500-600 600-700 700-800 800-900 900-1000 No. of lamps: 14 56 60 86 74 62 48 A bulb is selected at random. Find the probability that the life time of the selected bulb is : less than 400 between 300 to 800 hours at least 700 hours.

Explanation

(i)P(life time of the selected bulb is less than 400) = `"No. of bulbs having life time less than 400 hours"/"Total number of bulbs"`
`=14/400=7/200`
(ii)P(life time of the selected bulb is between 300 to 800 hours) = `"No. of bulbs having life time between 300 to 800 hours"/"Total number of bulbs"`
`=290/400=29/40`
(iii)P(life time of the selected bulb is at least 700 hours)= `"No. of bulbs having life time at least 700 hours"/"Total number of bulbs"`
`=184/400=23/50`