What is the probability of a security pass being yellow or having a chain?

[Chewy0087]

Homework Statement

The security passes for a certain company are coloured yellow or white, they're provided with either a clip or a chain. The probability that a pass has a clip is 6/10, 2/3 of the white passes and 4/7 of the yellow ones are fitted with clips. A member of the company is stopped on his way into work find the probability that;

The pass is yellow
The pass is yellow with a chain

If two people are stopped randomly as they enter find the probability that one pass will be yellow and the other white, and one will have a clip and the other a chain.

Homework Equations

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The Attempt at a Solution

Really frustrating question, is this question possible? :/ This is what I've tried, but it's wrong according to the book;

(3/7 * 4/10) + (4/7 * 6/10) = 0.514 (I know this is wrong but I was trying anything)

I just don't see how this is possible because surely it's dependent on the actual number that are white and yellow? Surely if there's 1000 white, and 5 yellow, the probability of a yellow is much different than with different numbers there, and they tell you no-where what to assume...

Any help would be great.

 

[Chewy0087]

Got it, sorry, i always post too early.