GRADE 8 CHAGING RATES EXERCISE |

**QUESTIONS**

Change the following rates into the indicated units:

Make sure to indicate the units in your answers.

- 1) A farmer has 200 laying hens who each lay 5 eggs per week.

How many dozen eggs per month can he produce? (there are 12 items in a dozen.) (

- 2) In the early 1950's a sprinter could do 2200 metres in 5 minutes.

What is that rate in kilometres per hour? (

- 3) The price of potatoes at the Atwater Market is $0.57 per 100 grams.

What is the price for a kilogram? (

- 4) A weird weatherman said "the wind is from the northeast at 50 metres per minute."

What is the wind speed in kilometres per hour? (

- 5) The winning horse in a race ran the 3.2 km track in 4.3 minutes.

What was his speed in kilometres per hour? (

- 6) Once launched, the space shuttle rose 3450 metres in 10 seconds.

What is the speed in kilometres per hour? (

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**SOLUTIONS**

1) 200 hens at 5 eggs/week each = 1000 eggs/week

1 month = 4 weeks so he gets 4000 eggs/month.

12 eggs/dozen makes it 4000/12 = 333.33 dozen eggs/month.

He can produce and sell **333 dozen eggs/month** and have 4 eggs left over for an omelette.

2) 2200 metres in 5 minutes = 2.2 km in 5 minutes

2.2 km in 5 minutes = 0.44 km/min

0.44 km/min % 60 min/hr = **26.4 km/hr**.

3) $0.57 per 100 grams: There are 1000 grams in a kilogram

1000 = 10 % 100 so it costs 10 % 0.57 = **$5.70** for a **kilogram** of potatoes.

4) 50 metres per minute = 50 % 1/1000 km/m = 1/20 km/min

There are 60 minutes in an hour so the speed is 1/20 km/min % 60 min/hr = **3 km/hr**.

5) 3.2 km in 4.3 minutes = 3.2/4.3 km/min = 0.74419 km/min.

There are 60 minutes in an hour so the speed is 0.74419 km/min % 60 min/hr = **44.65 km/hr**.

6) 3450 metres in 10 seconds = 345 m/sec = 0.345 km/sec

There are 3600 seconds in an hour so 0.345 km/sec % 3600 sec/hr = **1242 km/hr**.

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