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# In how many ways can 10 different marbles be distributed between 2 boys so that one of them get 7?

$\begin{array}{1 1} 240 \\ 120 \\ 21 \\ 14 \end{array}$

7 marbles from 10 marbles can be selected in $^{10}C_7$ ways.
1 boy from 2 boys can be selected in $^2C_1$ ways.
$\therefore$ The required no. of ways = $^{10}C_7.^2C_1$
$=120\times 2=240$