smc-892-40-Best buys

Number, NAP-L4-NC03

Santana is buying a guitar string.

Some of the strings are on sale.

Select the string that will be cheapest.

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`text(Sale: take 20% off)`

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`text(C)text(ost of each option:)`

`$17`

`$35\ text(less 50%) = $17.50`

`text($20 less 20%) = 20 – 4 = $16`

`text($24 less 25%) = 24 – 6 = $18`

`:.\ text(Sale: take 20% off is the cheapest string.)`

Number, NAP-C4-CA19

Pamela looks at the price of four sunscreens.

Which sunscreen is the cheapest per litre?

`text(Sun)`	`text(Sport)`	`text(Block)`	`text(Wet)`

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`text(Sport sunscreen)`

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`text(Sun)\ =1090/1200 = 0.91\ text(c/mL)`

STRATEGY: Finding the cost per mL is much more efficient in answering this question than finding the cost per litre.

`text(Sport)\ =540/600 = 0.9\ text(c/mL)`

`text(Block)\ =475/500 = 0.95\ text(c/mL)`

`text(Wet)\ =740/750 = 0.99\ text(c/mL)`

`:.\ text(Sport sunscreen is the cheapest per litre.)`

Number, NAP-D4-CA26

A company sells its iced tea in four different containers.

Which volume container has the cheapest price per mL?

`text(150 mL)`	`text(750 mL)`	`text(375 mL)`	`text(200 mL)`

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`text(375 mL)`

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`text(Consider the price per mL of each option)`

`text(150 mL :)\ \ 1.50/150 = 1\ text(cent/mL)`

`text(750 mL :)\ \ 6.10/750 = 0.81\ text(cent/mL)`

`text(375 mL :)\ \ 3.00/375 = 0.8\ text(cent/mL)`

`text(200 mL :)\ \ 1.80/200 = 0.9\ text(cent/mL)`

`:.\ text(375 mL is the cheapest price per mL)`

Number, NAP-I4-CA24

A shop sells four sizes of chocolate bar.

Which packet costs the least per gram?

`text(Packet 1)`	`text(Packet 2)`	`text(Packet 3)`	`text(Packet 4)`

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`text(Packet 2)`

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`text(Packet 1)`	`= 2.88/200 = 1.44\ text(c/g)`
`text(Packet 2)`	`= 310/220 = 1.41\ text(c/g)`
`text(Packet 3)`	`= 1.81/125 = 1.45\ text(c/g)`
`text(Packet 4)`	`= 4.97/350 = 1.42\ text(c/g)`

`:.\ text(Packet 2 costs the least per gram.)`

Number, NAP-I4-CA15

The table below lists the original price and the amount of discount of a pair of jeans at four different shops.

Which shop has the lowest sale price for the jeans?

`text(A)`	`text(B)`	`text(C)`	`text(D)`

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`text(Shop B)`

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`text(Consider the sale price at each shop:)`

`text(A)`	`= 20 – (25text{%} xx 20) = $15`
`text(B)`	`= 21 – (1/3 xx 21) = $14`
`text(C)`	`= 18 – (20 text{%} xx 18) = $14.40`
`text(D)`	`= 17 – 2 = $15`

`:.\ text(Shop B has the lowest sale price.)`