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A rate is a ratio that compares two different kinds of quantities. 2 teachers for 24 students: 2 teachers 24 students = 12 teacher students 15 strike-outs in 9 innings 15 strike-outs 9 innnings = strike-outs innings When you have a unit rate, the second quantity is 1. Example 240 miles in 4 hours. 240 miles 4 hours ÷ 4 4 = miles hour Suppose you drove to San Francisco in 3 hours. What would be the unit rate? don't forget the unit - mph 96 miles ÷ 3 hours = An easier way is to simply divide the distance by the time. ( miles per hour ) We use unit rates all the time. Many people are paid by the hour. Suppose you work at a coffee shop and make $9.50 an hour and work 8 hours. How much would you make? $9.50 x 8 hours = $76.00 Suppose you stayed late and worked 10 hours? $9.50 x your answer is money so it needs 2 decimals places and a $ sign = example - $75.00 An ice cream cone may be 35 calories per ounce. If the ice cream cone is 7 ounces, how many calories are in the ice cream cone. Suppose a different cone was 45 calories/ounce. How many calories would be in the whole cone? 35 calories/oz. x 7 ounces = 245 calories calories/oz. x don't forget the unit - calories oz. = Unit rates can be used to find the better buy. $1.20 ÷ 16 = $ A) 12 ounce can of soda for $.84 B) 16 ounce bottle for $1.20 $0.84 ÷ 12 = $ What's the better deal? / oz. / oz. 16 oz. bottle 12 oz. can What's the better buy? A) 4 oz. Snickers Bar for $0.80 B) 6 oz. 3 Musketeers Bar for $0.90 3 Musketeers Snickers There are 350 students in 11 classes. About how many students are in each class? Sometimes you just want to estimate the unit rate. Use compatible numbers. 350 ÷ 10 would be So what would be the best guess ( estimate )? 350 students per class 10 students per class 32 students per class 39 students per class students per class There are 123 students in 6 classes. About how many students are in each class? Sometimes you just want to estimate the unit rate. Use compatible numbers. 120 ÷ 6 would be So what would be the best guess ( estimate )? 15 students per class 18 students per class 21 students per class 6 students per class students per class |