Question

in a box there are 20 non defective and some defective bulbs. if the orobability that a bulb selected at random from the box found to be defective is 3 by 8 then, find the number if defective bulbs​

Answer 1

Answer:

Number of noneffective balls

= 20

Let

x

be defective balls

Number of total ball

= 20 + x

Therefore,

\frac{20}{20 + x}  =  \frac{3}{8} \\ 20 \times 8 = 3(20 + x) \\ 160 = 60 + 3x \\ 160 - 60 = 3x \\ 100 = 3x \\ x =  \frac{100}{3} \\ x = 33.33 \\ x = 33

Step-by-step explanation:

Answer 2

Answer:

let there be 'x' defective bulbs

probability of an event=No. of favourable outcomes / Total no. of outcomes.

P(E)=x/x+20=3/8

on solving you will get :-

x=12

The number of defective bulbs = 12

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