Tamil Nadu Board of Secondary EducationSSLC (English Medium) Class 10th

# In a box there are 20 non-defective and some defective bulbs. If the probability that a bulb selected at random from the box found to be defective is 38 then, find the number of defective bulbs - Mathematics

Sum

In a box there are 20 non-defective and some defective bulbs. If the probability that a bulb selected at random from the box found to be defective is 3/8 then, find the number of defective bulbs

#### Solution

Let the number of defective bulbs be “x”

Sample space (S) = 20 + x

n(S) = 20 + x

Let A be the event of getting to be defective

n(A) = x

P(A) = ("n"("A"))/("n"("S"))

⇒ 3/8 = x/(20 + x)

⇒ 8x = 3(20 + x) = (60 + 3x)

⇒ 8x – 3x = 60

⇒ 5x = 60

⇒ x = 60/5

⇒ x = 12

Number of defective bulbs = 12

Concept: Probability
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#### APPEARS IN

Samacheer Kalvi Mathematics Class 10 SSLC Tamil Nadu State Board
Chapter 8 Statistics and Probability
Exercise 8.3 | Q 10 | Page 324