Benny bought 120 t-shirts and shorts in total for a sports camp. The price of a t-shirt is $12.50 and the price of a pair of shorts is $11. The price of all the t-shirts is $301.50 more than the price of all the shorts.
a) How many pairs of shorts did Benny buy?
b) How much did he spend altogether?
P5 math. Please help my girl? Thanks.
Source: .
https://www.kiasuparents.com/kiasu/question/79669-2/
If you want to let your kid practice Guess-and-Check, can try below. Total Qty is 120. As kids progress with more complex methods, they may drop the “troublesome” Guess-and-Check method but it is still a good thing to practice once in a while until the big PSLE. Can also consider a little hybrid by making supposition (for every exchange) to save some time on guess and check. Still three sets of checking in below table.
| $ per T-shirt | Qty of T-shirts | Total $ T-shirts | $ per shorts | Qty of shorts | Total $ Shorts | Diff |
| $12.50 | let’s take 60 | $750 | $11 | 60 | $660 | $90 |
| suppose 61 | $762.50 | 59 | $649 | $113.50 | ||
| *see note | *see note | *see note | ||||
| 69 | $862.50 | 51 | $561 | $301.50 ok |
*analyse and deduce that for every one set of exchange from 1 pair of shorts to 1 T-shirt, Benny is spending $113.50-$90 = $23.50 more on T-shirts. (Or save $11 + spend $12.50 = $23.50 more on T-shirts)
$301.50 – $113.50 = $188.00
$188.00 / $23.50 = 8 more exchanges (–> 59-8 = 51 pairs of shorts) (–> 61+8 = 69 T-shirts).
Put back into table and check*
(a) 51 pairs of shorts#
(b) $862.50 + $561= $1423.50#
These questions are quantity/value questions. Common variations of the quantity/value within the question include animals / no. of legs, vehicles / no. of wheels, item / cost etc. The assumption method is just one way of solving it.
I prefer the table method below:
| Item | Quantity | Value | Total value (Quantity x Value) |
| T-shirt | 1 unit | $12.50 | $ (12.50 units) |
| Shorts | 120 – 1 unit | $11 | $ (1,320 – 11 units) |
a) 12.50 units = 1,320 – 11 units + 301.50
23.5 units = 1,621.5
1 unit = 69 T-shirts
120 – 69 = 51 pair of shorts
b) 69 x $12.50 = $862.50
51 x $11 = $561
$862.50 + $561 = $1423.50
