Remember: A rate says how much of one money buys another. Multiply to go one way, divide to go back. Rates can change, so check the sign before you swap.
Read and answer
Read the story first, then answer.
Ines and the kiteInes lived in Lumo, where money was a gold star coin, and she wanted a kite from Pell, where they made the best ones. In Pell, shops counted in tiles. The kite cost six tiles, but Ines had twenty-four star coins and no tiles. At the exchange booth a sign said, "One tile costs three star coins." That is an exchange rate: how much of one money buys one of another. Three stars buy one tile, six stars buy two, and every three more stars buy one more tile. Six tiles cost six times three, which is eighteen stars. Ines paid eighteen stars, got six tiles, bought the kite, and had six star coins left. A rate works both ways: to turn tiles into stars, multiply by three, and to go back, divide. A week later the sign said, "One tile costs four star coins." Nobody was cheating, because rates move all the time. Now six tiles cost twenty-four stars, so only the rate had changed, yet the kite cost six more stars. A kite in Lumo cost twenty-one stars. Real booths keep a little for their work, so swapping back gets slightly less.
1
At 3 star coins for a tile, 4 tiles cost stars.
2
Ines had 24 star coins and spent 18 on six tiles. She had star coins left.
3
To turn stars into tiles at 3 stars a tile, you ___.
add threemultiply by threedivide by three
4
Join each number of star coins to the tiles it buys at 3 stars a tile.
16 stars
212 stars
315 stars
424 stars
A5 tiles
B4 tiles
C8 tiles
D2 tiles
5
Number what Ines did, first to last.
She buys the kite with the tiles
She reads the sign: one tile costs three stars
She has six star coins left
She works out six tiles cost 18 stars
She pays 18 stars and gets six tiles
6
A week later one tile costs 4 stars. Six tiles now cost stars.
Think and fix
7
In week one the Pell kite cost 18 stars. A kite in Lumo costs 21 stars. Which kite was cheaper in week one?
The kite in LumoThe kite in PellThey cost the same
8
In week two the Pell kite costs 24 stars. That is more stars than the Lumo kite at 21.
9
Why can an exchange rate change from one week to the next?
More people may want one money than the otherThe booth keeper was cheatingThe kite got bigger
10
A real booth keeps a little for its work, so swapping there and back gets you slightly less.
TrueFalse
11
Fix the mistake. Ines says: the kite cost more in week two because the star coins shrank. Is Ines right?
YesNo
12
Stretch: in week two a tile costs 4 stars. Ines's 24 star coins buy tiles.
13
Ask a grown-up if they have seen an exchange rate on a sign. Write what it said.
14
Draw the exchange booth's sign for week one: one tile costs three star coins.
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