Permutation-Combination
Aptitude

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Q.

Ten coins are tossed simultaneously. In how many of the outcomes will the third coin turn up a head?

 A.

$2^{10}$

 B.

$2^9$

 C.

$3 × 2^8$

 D.

$\text{None of these}$

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Solution:
Option(B) is correct

When a coin is tossed once, there are two outcomes. It can turn up a head or a tail.

When 10 coins are tossed simultaneously, the total number of outcomes $= 2^{10}$

Out of these, if the third coin has to turn up a head, then the number of possibilities for the third coin is only 1 as the outcome is fixed as head.

Therefore, the remaining 9 coins can turn up either a head or a tail, $ = 2^9$


(1) Comment(s)


Abc
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Can u please elaborate the solution ...It's abstruse to some extent...