Sam packed 320 marbles into four boxes, labelled A, B, C and D. Box A had the most number of marbles and box D had the least. The difference in the number of marbles between Box A and the number of marbles in the other three boxes were 8, 13 and 19.
How many marbles were there in Box D?
D []<----- 19 -----> ]
C [][ 6 ]<-- 13 ---> ]
B [][ 11 ]<-- 8 --> ] 320
A [][ 19 ] ]
4 u --> 320 - 6 - 11 - 19 = 284 Small unit -- D
1 u --> 284 / 4 = 71
It is 71 marbles.
Alternative method (model drawing is actually not required)
------------------------
A [ ] ]
B [ ]<-- 8--> ]
C [ ]<-- 13 ---> ] 320
D [ ]<---- 19 --------> ]
4 u --> 320 + 8 + 13 + 19 = 360 Big units -- A
1 u --> 360 / 4 = 90
90 - 19 = 71
It is 71 marbles.
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As appeared in PSLE 2010 exam:
ReplyDeleteSam packed 320 marbles into four boxes, labelled A, B, C and D. Box A had the most number of marbles and box D had the least. The difference in the number of marbles between Box A and the number of marbles in the other three boxes were 8, 13 and 19.
How many marbles were there in Box D?
Yes, of course
ReplyDelete