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A preschool classroom has 20 three-year-olds and 10 four-year-olds. Th
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02 May 2022, 01:15
02 May 2022, 01:15
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A preschool classroom has 20 three-year-olds and 10 four-year-olds. The average height for the three-year-olds is 37 inches, and the average height for a four-year-old is 40 inches. What is the average height of the 30 students in the classroom?
A. 37 inches
B. 37.5 inches
C. 38 inches
D. 38.5 inches
E. 39 inches
A. 37 inches
B. 37.5 inches
C. 38 inches
D. 38.5 inches
E. 39 inches
Part of the project: GRE Quantitative Comparison & Problem Solving Challenge
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GRE Math Essentials for a TOP Quant Score - Q170!!! (2021)
GRE Geometry Formulas for a Q170
GRE - Math Book
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GRE Math Essentials for a TOP Quant Score - Q170!!! (2021)
GRE Geometry Formulas for a Q170
GRE - Math Book
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Re: A preschool classroom has 20 three-year-olds and 10 four-year-olds. Th
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02 May 2022, 05:36
02 May 2022, 05:36
1
Carcass wrote:
A preschool classroom has 20 three-year-olds and 10 four-year-olds. The average height for the three-year-olds is 37 inches, and the average height for a four-year-old is 40 inches. What is the average height of the 30 students in the classroom?
A. 37 inches
B. 37.5 inches
C. 38 inches
D. 38.5 inches
E. 39 inches
A. 37 inches
B. 37.5 inches
C. 38 inches
D. 38.5 inches
E. 39 inches
We can solve this question using weighted averages
Weighted average of groups combined = (group A proportion)(group A average) + (group B proportion)(group B average) + (group C proportion)(group C average) + ...
20/30 = 2/3. So, 2/3 of the students are three-year-olds (with an average height of 37 inches)
10/30 = 1/3. So, 1/3 of the students are four-year-olds (with an average height of 40 inches)
Plug these values into our formula to get:
Average height of the combined group = (2/3)(37) + (1/3)(40)
= 74/3 + 40/3
= 114/3
= 38
Answer: C
gmatclubot
Re: A preschool classroom has 20 three-year-olds and 10 four-year-olds. Th [#permalink]
02 May 2022, 05:36
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