Q. 135.0( 3 Votes )

# 80 bulbs are selected at random from a lot and their lifetime is recorded in the from of a frequency table given below:

A bulb is chosen at random from the lot. What is the probability that the bulb chosen has lifetime less than 900 hours?

A.

B.

C.

D.

Answer :

Total number bulbs= 80

Number of bulbs, which have lifetime of 300 hrs = 10

Number of bulbs, which have lifetime of 500 hrs = 15

Number of bulbs, which have lifetime of 700 hrs = 23

Number of bulbs, which have lifetime of 900 hrs = 25

Number of bulbs, which have lifetime of 1100 hrs = 7

Number of bulbs , having lifetime less than 900 hrs = 10 + 15 +23 = 48

Probability P() =

Probability of selecting a bulb which have a lifetime of 900 hrs

P(900) = = =

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