6741
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2011-02-01T00:00:01
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<p>At a cinema a child's ticket costs £$4.20$ and an adult's ticket costs £$7.70$. When a group of adults and children went to see a film, the total cost was £$C$, where $C$ is a whole number greater than $90$ and less than $96$.</p>
<p>What is the value of $C$?</p>
<p><br></br>
If you liked this problem, <a href="http://nrich.maths.org/public/viewer.php?obj_id=643&part=">here is an NRICH task</a> which challenges you to use similar mathematical ideas.</p>
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Both $£4.20$ and $£7.70$ are multiples of
$70p$, so $£C$ must also be a multiple of $70p$. The
only multiple of $70p$ between $£90$ and
$£96$ which is a whole number of pounds is
$£91$.<br></br>
<br></br>
$7$ children and $8$ adults cost $7\times £4.20+8\times
£7.70=£29.40+£61.60=£91$.<br></br>
<br></br>
Or<br></br>
<br></br>
$18$ children and $2$ adults cost $18\times £4.20 +
2\times £7.70 = £75.60 +
£15.40 = £91$.<br></br>
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Weekly Problem 41 - 2009
Numbers and the Number System
Counting