
Elementary Math Fractions, Percentages, Word Problems, Equations, Inequations, Factorization, Expansion 
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October 18th, 2018, 12:12 PM  #1 
Member Joined: Aug 2018 From: Warrington Posts: 50 Thanks: 1  Width of the river
You want to swim across the river. Before you get in the water you want to work out approximately how far it is to the other side. Use the map below to estimate the width of the river. The river is approximately metres wide This answer will be marked within a reasonable range. 
October 18th, 2018, 12:50 PM  #2 
Senior Member Joined: Feb 2016 From: Australia Posts: 1,734 Thanks: 605 Math Focus: Yet to find out. 
? A scale is given in the diagram. What are you struggling with exactly?

October 18th, 2018, 01:05 PM  #3 
Member Joined: Aug 2018 From: Warrington Posts: 50 Thanks: 1 
how to work out the scale

October 18th, 2018, 02:05 PM  #4 
Math Team Joined: Jul 2011 From: Texas Posts: 2,773 Thanks: 1427 
so ... what would you estimate the width to be? 
October 18th, 2018, 11:00 PM  #5 
Member Joined: Aug 2018 From: Warrington Posts: 50 Thanks: 1 
20m i would say

October 19th, 2018, 12:07 AM  #6 
Senior Member Joined: Apr 2014 From: UK Posts: 891 Thanks: 328 
Are you estimating the width where the dotted line is, which is also where skeeter has pasted a rotated scale in his post?

October 19th, 2018, 12:58 AM  #7 
Global Moderator Joined: Dec 2006 Posts: 19,868 Thanks: 1833 
The dashed line seems to correspond to about 29 m.

October 21st, 2018, 06:47 PM  #8 
Senior Member Joined: May 2016 From: USA Posts: 1,189 Thanks: 489 
Set a compass so that the legs are set to equal 20 on the scale. Now place one leg at one end of the dotted line. Without moving the first leg, place the other leg on the dotted line. Does the compass reach all the way across? Not at all. So the width is more than 20. Now swing the compass keeping the leg on the dotted line still. Now does the other leg reach the other side. Yes, and far beyond it. So the width is less than 30. Reset the compass on the scale for 10. You will find that three measurements are pretty close, but a little bit more. So almost 30, but not quite. 29 is a reasonable approcximation. 
October 21st, 2018, 06:49 PM  #9 
Senior Member Joined: Aug 2012 Posts: 2,076 Thanks: 593  

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