Question 150 of 417MediumMCQ
Five numbers x1<x2<x3<x4<x5 are randomly selected from 1,…,18 (increasing order). The probability that x2=7 and x4=11 is: Solutions · 1
Official solution
n(S)=18C5; n(E)=6C1×3C1×7C1 (choices below 7, between 7\&11, above 11).
\[P = \frac{6\times3\times7}{{}^{18}C_5} = \frac{1}{68}\] Answer the question to unlock