# A Box Contains 100 Bulbs, 20 of Which Are Defective. 10 Bulbs Are Selected for Inspection. Find the Probability that All 10 Are Good - Mathematics

A box contains 100 bulbs, 20 of which are defective. 10 bulbs are selected for inspection. Find the probability that all 10 are good

#### Solution

Out of 100 bulbs, 10 can be chosen in 100C10 ways.
So, total number of elementary events = 100C10\

The number of ways of selecting 10 non-defective bulb out of 80 is 80C10 ways.
∴ Favourable number of elementary events = 80C10
Hence, required probability = $\frac{^{80}{}{C}_{10}}{^{100}{}{C}_{10}}$

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#### APPEARS IN

RD Sharma Class 11 Mathematics Textbook
Chapter 33 Probability
Exercise 33.3 | Q 44.2 | Page 48

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