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Probability Level 4

Assuming the balls to be identical except for difference in colors, the number of ways in which one or more balls can be selected from 10 white, 9 green and 7 black balls is

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The answer is 879.

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Harshvardhan Mehta by Harshvardhan Mehta , 23, India

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1 solution

Required number of ways are given by

(10 + 1)(9 + 1)(7 + 1) - 1

= 11 * 10 * 8 - 1

=879

7 Helpful 0 Interesting 0 Brilliant 0 Confused

Can you explain please ?

Kudou Shinichi - 6 years, 5 months ago

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Number of ways of selecting white balls=11 (Pick up 0/1/2/3/.../10 balls)

Number of ways of selecting green balls =10

Number of ways of selecting black balls=8

So total number of ways=11×10×8. (You know why I multiplied?)

One case will be none picked up.

So our answer will be 880-1=879.

Pranjal Jain - 6 years, 4 months ago

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yeah, similar approach

Honey Singh - 6 years, 4 months ago

Thanks Pranjal

Kudou Shinichi - 6 years, 4 months ago

Think of it as:

the required answer is the total ways of selecting the balls minus the no of ways you can select 0 balls.

A Former Brilliant Member - 6 years, 4 months ago

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Thanks Anup

Kudou Shinichi - 6 years, 4 months ago

Applied Same approach!

Rajat Bisht - 6 years, 5 months ago

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