the ratio of lemon juice to water in lemonade is 3:7 ,. if 9 cups of water aer used to make a pitcher of lemonade , how many cups of lemon juice are needed

Make a proportion. Let x = lemon juice

3/7 = x/9

Cross multiply and solve for x.

http://www.purplemath.com/modules/ratio4.htm

3.86

To find out how many cups of lemon juice are needed, we can use the given ratio of lemon juice to water, which is 3:7.

Step 1: Calculate the total number of parts in the ratio.
The total number of parts in the ratio is 3 + 7 = 10.

Step 2: Determine the ratio of water to lemon juice in terms of cups.
Since we know that 9 cups of water are used in the pitcher of lemonade, we need to find the corresponding amount of lemon juice.

Step 3: Calculate the number of parts of lemon juice.
To determine the number of parts of lemon juice, we need to use the part-to-part property of an equivalent ratio. Since the ratio of lemon juice to water is 3:7, the ratio of lemon juice to cups of water should also be 3:7.

Step 4: Calculate the cups of lemon juice needed.
To find out how many cups of lemon juice are needed, we need to divide the total number of parts (10) by the number of parts of lemon juice (3).

So, (9 cups of water x 3 parts of lemon juice) / 7 parts of water = 27 cups of lemon juice / 7 = approximately 3.857 cups of lemon juice.

Therefore, approximately 3.857 cups of lemon juice are needed to make the pitcher of lemonade.