A term is randomly chosen from the expansion of 4 6 + 1 5 4 20 . If the probability that it is a rational term is P , then 420 P is equal to

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Question: Answered & Verified by Expert

A term is randomly chosen from the expansion of

{(\sqrt[6]{4} + \frac{1}{\sqrt[4]{5}})}^{20} .

If the probability that it is a rational term is

P

, then

420 P

is equal to

MathematicsProbabilityJEE Main

Solution:

2961 Upvotes Verified Answer

The correct answer is: 40

Total number of terms

= 21

Number of rational terms

= 2

(

9^{t h}

and

21^{st}

)
Required probability

(P) = \frac{2}{21}

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