A student has to answer 10 out of 13 questions in an examination. The number of ways in which he can answer if he must answer atleast 3 of the first five questions is

Question

Aicharya · Accepted Answer

Total number of ways $ \begin{aligned} & ={ }^5 C_3{ }^8 C_7+{ }^5 C_4{ }^8 C_6+{ }^5 C_5{ }^8 C_5 \ & =10 	imes 8+5 	imes 28+1 	imes 56 \ & =80+140+56=276 \end{aligned} $

A student has to answer 10 out of 13 questions in an examination. The number of ways in which he can answer…

Solution