Four boys and three girls stand in a queue for an interview, prob… - Vidyadip

MCQ

Four boys and three girls stand in a queue for an interview, probability that they will in alternate position is

A
$\frac{1}{{34}}$
✓
$\frac{1}{{35}}$
C
$\frac{1}{{17}}$
D
$\frac{1}{{68}}$

✓

Answer

Correct option: B.

$\frac{1}{{35}}$

b
(b) Four boys can be arranged in $4\,!$ ways and three girls can be arranged in $3\,!$ ways.

$\therefore $ The favourable cases $ = 4\,!\, \times \,3\,!$

Hence the required probability $=\frac{{ 4\,!\, \times 3\,!}}{{7\,!}} = \frac{6}{{7 \times 6 \times 5}} = \frac{1}{{35}}$.

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