(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

I've spent a few hours but unable to work out the solution of the following questions successfully.

The question is as follows:

I am having problems with (a)(iii) and (b)(ii)

2. Relevant equations

3. The attempt at a solution

(a)(iii) Although I can work out the solution at last, my original attempt was incorrect but I don't understand why.

My first attempt:

P(pass) = P(4 answer correct) + P(5 answer correct) + P(all answer correct)

= (3x3x1x1x1x1)/(6x6x6x6x6x6) + (3x1x1x1x1x1)/(6x6x6x6x6x6) + (1x1x1x1x1x1)/(6x6x6x6x6x6)

However, this is wrong. But I don't understand why............

(b)(iii) I can't work out the solution at all. Please help. Thank you.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Another conditional probability problem

**Physics Forums | Science Articles, Homework Help, Discussion**