There are 4 green marbles and x x\,x yellow marbles in a jar.
Noah takes a marble from the jar at random.
He puts the marble back into the jar.
Noah then takes another marble at random from the jar.
The probability that the first marble Noah takes is green and the second marble Noah takes is green is 116\displaystyle \frac{1}{16}161
Work out how many yellow marbles are in the jar.
Practise OCR GCSE Maths Probability Equation Questions with exam-style questions for Foundation and Higher tier. 28 questions, matched to the OCR GCSE Maths (J560) specification and written in the written papers style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.