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  • 80 bulbs are selected at random from a lot and their life time (in hrs) is recorded in the form of a frequency table given below : The probability that bulbs selected randomly from the lot has life less than 900 hours is :

80 bulbs are selected at random from a lot and their life time (in hrs) is recorded in the form of a frequency table given below :

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

The probability that bulbs selected randomly from the lot has life less than 900 hours is :

 (A)\ \frac{11}{40}

 (B)\ \frac{5}{16}

 (C)\ \frac{7}{16}

(D) \ \frac{9}{16}

 

Answers (1)

Answer: D

\text {P}=\frac{\text {favourable outcome}}{\text {Total outcomes}}

Bulb’s life is given as less than 900 hours = Bulbs with life 300, 500 and 700 hours

From the table, we can see that bulbs with life less than 900 hours =10+12+23

\text {P}=\frac{\text {favourable outcome}}{\text {Total favourable outcomes}}=\frac{45}{10+12+23+25+10}

=\frac{45}{80}=\frac{9}{16}

Therefore option (D) is correct.

Posted by

infoexpert23

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