Grade 10 — Mathematics 10-3 › T3U09 Unit Pricing & Currency Exchange

Grade 10 › T3U09 Unit Pricing & Currency Exchange › L3
GRADE 10 · ALBERTAOUTCOME AB-MAT10-3-N1

L3 · Currency Exchange: Buy Rate vs Sell Rate

Learning goal

“I can convert between Canadian dollars and a foreign currency using the rate board - choosing the exchange office's SELLING rate when I buy foreign money and its PURCHASING (buy) rate when I change money back - using unit rates and rate tables only.”

Exchange rate — the price of one currency in terms of another: 1 USD = 1.38 CAD means one US dollar costs 1.38 Canadian dollars.
Selling rate — the rate at which the bank or exchange office SELLS foreign currency to you. This is the rate you pay when you buy foreign money before a trip.
Purchasing (buy) rate — the rate at which the office BUYS foreign currency from you. This is the rate you receive when you change leftover money back.
Unit rate (exchange) — the rate stated per 1 unit of foreign currency, the form every conversion in this lesson scales from.
Worked example

The board at an exchange office reads: "We SELL US dollars: 1 USD = 1.38 CAD. We BUY US dollars: 1 USD = 1.31 CAD." You are leaving for a trip and want to buy 200 USD. Which rate? Step 1: YOU are buying; the OFFICE is selling. Use the selling rate: 1 USD costs 1.38 CAD. Step 2: Scale the unit rate: 200 USD x 1.38 CAD per USD = 276. You pay $276 CAD. On the rate table: 1 USD -> 1.38 CAD; 10 USD -> 13.80; 100 USD -> 138; 200 USD -> 276 CAD. Say it plainly: the office sells high and buys low - that gap is how it gets paid. The rate in the news (say, 1 USD = 1.34 CAD) sits between the two board rates and is charged by nobody.

Check yourself — explain it

Before a trip you use the selling rate because...

Paired problem — example still visible

At a selling rate of 1 EUR = 1.47 CAD, how much do 50 euros cost? -> 50 x 1.47 = $73.50 CAD

Faded completion — last step is yours

"Buying 25 GBP at 1 GBP = 1.74 CAD: cost = 25 x ___ = $___" -> 1.74; 43.50

Ready to practise?

10 scored questions with a 3-rung hint ladder. Mastery needs 8/10 plus both gate questions.

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