To solve a ratio for a missing value, we usually use a proportion to identify the missing number, the variable.
Using the examples from the previous journal entry, we will solve for a missing value under a hypothetical, or "pretend", situation. Set up a proportion for each problem.
1) 5 plates for 2 bowls, how many plates if there are 6 bowls? 15 plates
2) 2 boys: 3 girls, how many girls if there are 12 boys? 18 girls
3) 4 blue blocks to 6 red blocks, how many blue blocks if there are 12 red blocks? 8 blue blocks
Below is an image of different ways to set up the proportion to solve.
Below is a basic ratio word problem as an example of how to solve to find the missing value.
Not all word problems will provide 2 matching units. Sometimes you will be given 3 units that don't seem to match together at all, like the word problem below.
Try some problems like the one from the Sally's test in the video:
1) 5 plates for 2 bowls, how many of each if there are 21 total? 15 plates, 6 bowls
2) 2 boys: 3 girls, how many of each if there are 30 total? 12 boys, 18 girls
3) 4 blue blocks to 6 red blocks, how many of each if there are 60 total? 24 blue blocks, 36 red blocks
4) 3 made shots for every 5 attempts, how many MISSES if there are 20 total attempts? 8 missed shots
Classwork - Ratio word problems
1. A recipe calls for 6 eggs to make 15 pancakes. How many eggs are needed to make 70 pancakes?
2. Sandra drove 126.2 miles in 2 hours at a constant speed. How long would it take her to drive 189.3 miles at the same speed?
3. Carmen earned $144 for 18 hours of work. At this rate, how much will she earn for 36 hours of work?
4. Nine apples cost $2.61. How much will 4 dozen apples cost?
5. In order to determine her pulse rate, Sondra’s nurse count 23 beats in 20 seconds. At this rate, how many beats would she have in 1 minute?
6. Parker uses a cookie recipe that requires ¾ cup of sugar to make 33 cookies. If Parker only wants to make 11 cookies, how much sugar should he use?