Bissoy.com
Doctors Medicines MCQs Q&A

A box contains nine bulbs out of which 4 are defective. If four bulbs are chosen at random, find the probability that exactly three bulbs are good.

A box contains nine bulbs out of which 4 are defective. If four bulbs are chosen at random, find the probability that exactly three bulbs are good. Correct Answer $$\frac{{20}}{{63}}$$

Required probability
$$\eqalign{ & = \frac{{{}^5{C_3}\,.\,{}^4{C_1}}}{{{}^9{C_4}}} \cr & = \frac{{10 \times 4}}{{126}} \cr & = \frac{{20}}{{63}} \cr} $$

Related Questions

Directions: Seven different boxes A, B, C, D, E, F and G of different colours viz., Orange, Pink, Purple, Yellow, Blue, Red and Green are arranged one above the other. The box at the bottom of arrangement is numbered 1, the above box is numbered 2 and so on. B is immediately above E. More than two boxes are above the Orange box. The Yellow box is immediately below A. Only one box is between the Orange box and F. G is immediately above the Red box. Only one box is between B and the Pink box. Only two boxes are between the Pink and the Green box. Only two boxes are between the Yellow box and the Orange box. The Purple box is neither at the top nor at the bottom of the arrangement.B is above Pink box. C is immediately above F. Neither C nor G is a Yellow box. G is not a Orange box. Question: Which combination represents the position of C and its colour?
A box contains nine bulbs out of which 4 are defective. If four bulbs are chosen at random, find the probability that all the four bulbs are defective.
Five boxes B1, B2, B3, B4 and B5 are placed one above the other in racks. The lowermost rack is numbered as one and just above the lowermost is numbered as two and so on. Each box is coloured with different colour such as L1, L2, L3, L4 and L5 (not necessarily in the same order). Two boxes are placed between L2 coloured box and L5 coloured box. Box B1 is not placed immediately above box B3. Box B4 is placed in the top most rack. L1 coloured box is placed immediate above L5 coloured box. Box B3 is coloured with L4. L5 coloured box is placed above L4 coloured box. Box B2 is coloured with L1. Which of the following boxes are placed immediately above and immediately below B5 box respectively?
If a box contains 10 bulbs,of which just three are defective. If a random sample of five bulbs is drawn, find the probability that the sample contains no defective bulbs.
A box contains nine bulbs out of which 4 are defective. If four bulbs are chosen at random, find the probability that at least one bulb is good.
A box contains 10 electric bulbs from which 2 bulbs are defective . Two bulbs are chosen at random. What is the probability that one of them is defective?
a box contains 20 electric bulbs , out of which 4 are defective . 2 bulbs are chosen at random from this box . The probability that at least one of these is defective is
A box contains 20 electric bulbs, out of which 4 are defective. Two bulbs are chosen at random form this box. The probability that at least one of these is defective is ___
A box contains 10 bulbs,of which just three are defective. If a random sample of five bulbs is drawn, find the probability that the sample contains exactly one defective bulb.
Six boxes - A, B, C, D, E and F are placed around a circular table. Box C is placed fifth to the left box E. Box D is opposite to the box E. Box A is placed between box C and box D. Box B is placed adjacent to box E. Which box is exactly placed between box F and E?