JEE Advance - Mathematics (1988 - No. 4)
A box contains $$2$$ fifty paise coins, $$5$$ twenty five paise coins and a certain fixed number $$N\,\,\left( { \ge 2} \right)$$ of ten and five paise coins. Five coins are taken out of the box at random. Find the probability that the total value of these $$5$$ coins is less than one rupee and fifty paise.
$$\,1 - {{10left( {N + 2}
ight)} over {\binom{N + 7}{5}}}$$
$$\,1 - {{5left( {N + 2}
ight)} over {\binom{N + 7}{5}}}$$
$$\, {{10left( {N + 2}
ight)} over {\binom{N + 7}{5}}}$$
$$\, {{5left( {N + 2}
ight)} over {\binom{N + 7}{5}}}$$
$$\,1 - {{10left( {N - 2}
ight)} over {\binom{N + 7}{5}}}$$