Weekly Maths Challenge

Seven Day Maths

Challenge 174: Sporting Selections

It’s the time of year for Sports Day, and in each tutor group, every student must sign up either to run, or to jump, or to throw for the tutor group team.

In one particular tutor group there are 15 students, including one pair of twins and one set of triplets. As nobody in this group remembers to sign up before Sports Day, the tutor allocates, at random, five students to running, five to jumping and five to throwing.

What is the probability that the twins end up doing the same activity but that the triplets are all doing something different?

Mathematics is a subject where you learn best by tackling problems. Every week, a new problem will be posted here for you to pit your wits against.

We invite you to have a go at solving it. If you get stuck, keep trying, and do go away and come back later – you will often find that you have a better idea on your second, third or even fourth attempt. If you have solved the problem, you can send your solutions to weeklymaths@kcl.ac.uk. You are welcome to either scan in written work, or to type your solutions. If you are emailing for the first time, please let us know what year you are currently in and what school you are at.

Past problems can be accessed below, and we welcome submissions of solutions for those too.

Follow us on Twitter here: @sevendaymaths, so that you never miss a new problem being posted!

Good luck!

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Weekly Challenge 173

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