'Plausible Estimation' Estimating for 
Amazing Facts Tasks - Set #3


Malcolm Swan
Mathematics Education
University of Nottingham
Malcolm.Swan@nottingham.ac.uk

Jim Ridgway
School of Education
University of Durham
Jim.Ridgway@durham.ac.uk


The aim of this assessment is to provide the opportunity for you to:
· develop a chain of reasoning that will enable you to estimate quantities to an appropriate 
degree of accuracy
· choose suitable units for your estimate
· communicate the assumptions upon which your estimate is based.

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1. High stack

 
Suppose you have a very large sheet of paper. You tear it in half and put one half on top of the 
other. You now have a stack of two sheets.

You now tear the whole stack in half and place one half on top of the other to make a new stack. 
You repeat this process, tearing 50 times. (Yes I know its impossible - just imagine you could).

 How high would the stack be? 50 feet? 100 feet? A mile? or more...?  Make a sensible estimate, 
based on careful reasoning. 

Assumptions










Reasoning













2. The swimming pool and the glass.

 
How long would it take you to empty an olympic size swimming pool with a glass?










Assumptions










Reasoning













3. The briefcase of cents

     

Suppose you filled a briefcase with one cent coins.

How much would the money be worth?





Assumptions










Reasoning