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Sunday, April 24, 2011

ACS Primary 2010 SA1 Math Paper 2 Q15

Both Joanne and Joseph had an equal amount of money at first. Every month, Joanne spent $850 and Joseph spent $912. After a few months, Joanne was left with $1550 while Joseph had 4/5 as much as Joanne. How much money did Joseph have at first?

Solution


Every month,
Joanne spends $850
Joseph spends $912
Difference every month
--> $912 - $850 = $62


After a few months, Joseph had 4/5 as much as Joanne,


5 units ----- $1550
1 unit ------ $1550 divided by 5 = $310
($310 is the difference between Joanne and Joseph after a certain number of months)


Number of months to achieve the $310 difference,
$310 divided by $62 = 5 (mths)
It also takes 5 months for Joseph to have 4/5 as much as Joanne.


Amount Joseph has at first,
Joseph ------ 4 units + (5 mths x $912 spent per mth)
----- (4 x $310) + (5 x $912)
= $1240 + $4560
= $5800

Answer: $5800


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