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09 Aug 2018, 23:29
Kudos
Bookmarks
As with many GMAT questions, there are many ways to arrive at the answer to this question! I am adding my two cents as part of my new project to go through all of the Quant questions in the 2019 Official Guide and share my suggested "GMAT Timing Tips" for each one: that is, what could you notice or do to be able to answer each question more efficiently? For this question, my GMAT Timing Tips are:
I'm also planning to create video solutions demonstrating how to use my GMAT Timing Tips for each of the Official Guide Quant questions. This will take a while, but I'll start with the those that I get requests for first. If you would me to create a video solution for this question, please go to the page that I have created for this question and vote for or share it: Of the 84 parents who attended a meeting at a school, 35..
You can also ask me to answer a question about this GMAT practice question by asking it in this thread, or by using the question form on the page above, and I'll address it in my video solution. Please let me know if you have any questions!
- Two-set Venn Diagrams: Draw out the Venn Diagram to quickly see how the numbers you are given relate to what you are asked to calculate. As many people have done on this thread, you can find that 24 parents volunteered only to supervise children.
- Use smart variables to represent unknowns: I recommend using the variable R to represent the total number of parents who volunteered to bring refreshments, because that is what the question asks us to solve for. Then, using the Venn Diagram and the information in the question, write the equation R = 1.5(84 - 24 - R), and just solve for R.
I'm also planning to create video solutions demonstrating how to use my GMAT Timing Tips for each of the Official Guide Quant questions. This will take a while, but I'll start with the those that I get requests for first. If you would me to create a video solution for this question, please go to the page that I have created for this question and vote for or share it: Of the 84 parents who attended a meeting at a school, 35..
You can also ask me to answer a question about this GMAT practice question by asking it in this thread, or by using the question form on the page above, and I'll address it in my video solution. Please let me know if you have any questions!
06 Sep 2020, 14:21
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Bunuel
Solution:
We can use the following formula:
Total = Picnic + Refreshment - Both + Neither
We are given that Total = 84, Picnic = 35, Both = 11, and Refreshment = 1.5 x Neither. Thus, if we let n = Neither, we have:
84 = 35 + 1.5n - 11 + n
84 = 24 + 2.5n
60 = 2.5n
n = 60/2.5 = 600/25 = 24
Since Refreshment = 1.5 x Neither, then Refreshment = 1.5 x 24 = 36.
Answer: B
11 Jun 2023, 07:29
Kudos
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Let's break down the information given in the problem to determine the number of parents who volunteered to bring refreshments.
We are given:
-Total number of parents who attended the meeting: 84
-Number of parents who volunteered to supervise children during the picnic: 35
-Number of parents who volunteered both to supervise children and bring refreshments: 11
To find the number of parents who volunteered to bring refreshments, we need to determine the number of parents who neither volunteered to supervise children during the picnic nor volunteered to bring refreshments.
Let's denote:
-Number of parents who volunteered to bring refreshments: x
-Number of parents who neither volunteered to supervise nor bring refreshments: y
We know that the number of parents who volunteered to bring refreshments was 1.5 times the number of parents who neither volunteered to supervise nor bring refreshments. So, we can write the equation:
x = 1.5y
Now, let's set up an equation using the given information about the total number of parents:
Total parents = Parents who volunteered to supervise + Parents who volunteered to bring refreshments - Parents who volunteered both + Parents who neither volunteered
84 = 35 + x - 11 + y
Rearranging the equation, we have:
84 = x + y + 24
Since we know x = 1.5y, we can substitute this value into the equation:
84 = 1.5y + y + 24
84 = 2.5y + 24
60 = 2.5y
y = 24
Now, we can find the value of x by substituting the value of y into the equation x = 1.5y:
x = 1.5 * 24 = 36
Therefore, the number of parents who volunteered to bring refreshments is (B) 36.
We are given:
-Total number of parents who attended the meeting: 84
-Number of parents who volunteered to supervise children during the picnic: 35
-Number of parents who volunteered both to supervise children and bring refreshments: 11
To find the number of parents who volunteered to bring refreshments, we need to determine the number of parents who neither volunteered to supervise children during the picnic nor volunteered to bring refreshments.
Let's denote:
-Number of parents who volunteered to bring refreshments: x
-Number of parents who neither volunteered to supervise nor bring refreshments: y
We know that the number of parents who volunteered to bring refreshments was 1.5 times the number of parents who neither volunteered to supervise nor bring refreshments. So, we can write the equation:
x = 1.5y
Now, let's set up an equation using the given information about the total number of parents:
Total parents = Parents who volunteered to supervise + Parents who volunteered to bring refreshments - Parents who volunteered both + Parents who neither volunteered
84 = 35 + x - 11 + y
Rearranging the equation, we have:
84 = x + y + 24
Since we know x = 1.5y, we can substitute this value into the equation:
84 = 1.5y + y + 24
84 = 2.5y + 24
60 = 2.5y
y = 24
Now, we can find the value of x by substituting the value of y into the equation x = 1.5y:
x = 1.5 * 24 = 36
Therefore, the number of parents who volunteered to bring refreshments is (B) 36.
