Henry Park Pri Sch 2007 PSLE Math Prelim Q47

At first, Bob had only $5-notes and Chris had only $2-notes. The number of notes Bob had is 80% of Chris’ notes. When Bob gives Chris $100, the number of notes Chris has now is 70% more than Bob.
a) How many notes did Bob have at first?
b) How much money does Chris have at the end?

Solution

a) When Bob gave $100 to Chris, Bob gave Chris 20 notes because Bob had only $5 notes ----- $100 divided by $5 notes = 20 $5-notes.




(Bob) 136% - 34 notes ----- 100% + 20 notes (Chris)
136% - 100% ----- 34 notes + 20 notes
36% ----- 54 notes
1 % ----- 54 divided by 36 = 1.5
80% ----- 1.5 x 80 = 120

Answer: Bob had 120 notes at first.

b) Chris had at the end ----- (100%) + 20 notes

100% ----- 100 x 1.5 = 150 (notes)
150 notes x $2 = $300

20 notes x $5 (given by Bob)
= $100

$300 + $100 = $400

Answer: Chris had $400 in the end.