Ashley, Sophia, Elizabeth and Alexis have to walk through a long dark tunnel. They only have one torch between them so a maximum of two people can go through the tunnel at any one time. Each person takes a different amount of time to get through the tunnel and if two people walk together they must walk at the rate of the slowest.
Ashley takes 2 minutes, Sophia takes 5 minutes, Elizabeth takes 9 minutes, Alexis takes 12 minutes. What is the least amount of time for all four to walk through the tunnel? 
Notes: 
Example:
If Elizabeth and Alexis walk through the tunnel together it will take 12
minutes, If Elizabeth then walks the torch back through the tunnel a total of 21 minutes will have passed. Continue till all four are at the other end of the tunnel.
Topics: Starter  Logic  Problem Solving  Puzzles
How did you use this starter? Can you suggest
how teachers could present or develop this resource? Do you have any comments? It is always useful to receive
feedback and helps make this free resource even more useful for Maths teachers anywhere in the world.
Click here to enter your comments.
Previous Day  This starter is for 8 February  Next Day
Sign in to your Transum subscription account to see the answers
Note to teacher: Doing this activity once with a class helps students develop strategies. It is only when they do this activity a second time that they will have the opportunity to practise those strategies. That is when the learning is consolidated. Click the button above to regenerate another version of this starter with different numbers and names.
Your access to the majority of the Transum resources continues to be free but you can help support the continued growth of the website by doing your Amazon shopping using the links on this page. Below is an Amazon link. As an Amazon Associate I earn a small amount from qualifying purchases which helps pay for the upkeep of this website.
Educational Technology on Amazon
GCSE Revision and PracticeWhatever exam board you use for GCSE Mathematics, this book by David Rayner remains an allround winner. With this latest edition presented in full colour and completely updated for the new GCSE(91) specifications, this uniquely effective text continues to increase your chance of obtaining a good grade. This book is targeted at the Higher tier GCSE, and provides a wealth of practice with careful progression, alongside substantial revision support for the newstyle grading and exam questions. With all the new topics included, and a dedicated section on using and applying mathematics, this unique resource can be used either as a course book over two or three years or as a revision text in the runup to exams. more... #ad 
Teacher, do your students have access to computers such as tablets, iPads or Laptops? This page was really designed for projection on a whiteboard but if you really want the students to have access to it here is a concise URL for a version of this page without the comments: Transum.org/go/?Start=February8 However it would be better to assign one of the student interactive activities below. 

Here is the URL which will take them to Tran Tunnels, a mathematical adventure.