 # Question

Hi,

I get this question from the assessment book.

In a sale, Nancy spent \$2960 on some blouses and skirts. Each blouse cost \$32 and each skirt cost 25% as much as each blouse. She bought 20 more skirts than blouses. How many skirts did she buy?

Ans : 25% x \$32 = \$8

\$32 + \$8 + \$40

20 x \$8 = \$160

(\$2960 – \$160) ÷ 40 = 70

70 + 20 = 90

I cannot understand why the last part is divided by 40. Isn’t it blouses and skirts share the unit ?

My understanding is as follow:

(\$2960 – \$160)= \$2800

\$2800 ÷ 2 = \$1400

\$1400 + \$160 = \$1560

\$1560 ÷ 40 = 39

39 + 20 = 59

Hi Musicstar. I believe your confusion Is the cost of each skirt. The skirt does not cost 125%. It costs 25% of blouse and so it is only \$8 each. \$40 is 1 set of 1 blouse and 1 shirt.

Taking away the cost of excess 20 skirts (\$160), the remainder \$2800 is 70 sets of 1 blouse and 1 shirt (\$40 per set)

So there are 90 skirts (70+20).

Oh. Maybe your confusion is not that, could be you think the balance cost \$2800 is shared equally between equal no. of blouses and skirts.

If so this is a misconception. Think about those coins type questions.

5pcs of \$1-coins and 5pcs of 20c-coins in the piggy bank (total \$6) doesn’t mean \$3 of \$1-coins and \$3 of 20c-coins.

solution should be: total value/value per set = no. of sets

misconception: half total value / value per pc = no. of pcs

If your algebra is good, you can deduce the same thing from Khong’s workings / Ender’s picture.

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0 Replies 0 Likes My understanding is as follow:

(\$2960 – \$160)= \$2800

From here onwwards is wrong.

\$2800 ÷ 2 = \$1400          X
\$1400 + \$160 = \$1560    X
\$1560 ÷ 40 = 39                X
39 + 20 = 59                       X

When you minus \$160 and left \$2800, it does not mean the cost of the skirt is half of it. It just means for the same number of skirts and blouses, they cost \$2800 together.

Refer to my picture for understanding how the \$2800 is breakdown. You will realized that the skirt do not cost half of \$2800 as what you have initially thought.

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