In a multiple choice question, there are four alternative answers of which one or more than one is correct A candidate will get marks on the question only if he ticks the correct answer. The candidate decides to tick answers at a random. If he is allowed up to three chances to answer the question, then find the probability that he will get marks on it.

Answer

A

Explanation

The total number of ways to answer the equestion
`=""^(4)C_(1)+""^(4)C_(2)+""^(4)C_(3)+""^(4)C_(4)=2^(4)-1=15`
`P("getting marks")=P("correct answer in I chance")+p("correct answer in II chance")+P("correct answer in III chance")`
`=(1)/(15)+((14)/(15).(1)/(14))+((14)/(15).(13)/(14).(1)/(13))=(3)/(15)=(1)/(5)`