In Lee Middle School, the ratio of the number of fifth-graders to the number of sixth-graders is 5 to 4, and there are 16 more fifth-graders. If the ratio of the number of sixth-graders to the number of seventh-graders is 2 to 3, what is the mean number of students in the three grades? Your Answer:
In Lee Middle School, the ratio of the number of fifth-graders to the number of sixth-graders is 5 to 4, and there are 16 more fifth-graders. If the ratio of the number of sixth-graders to the number of seventh-graders is 2 to 3, what is the mean number of students in the three grades? Your Answer:
Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
Section: Chapter Questions
Problem 1RQ
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![### Problem Statement:
**In Lee Middle School, the ratio of the number of fifth-graders to the number of sixth-graders is 5 to 4, and there are 16 more fifth-graders. If the ratio of the number of sixth-graders to the number of seventh-graders is 2 to 3, what is the mean number of students in the three grades?**
---
**Your Answer:**
[Text Box for User Input]
---
### Explanation:
In this problem, we need to find the mean number of students in the fifth, sixth, and seventh grades given the following ratios and information:
1. The ratio of fifth-graders to sixth-graders is 5:4.
2. There are 16 more fifth-graders than sixth-graders.
3. The ratio of sixth-graders to seventh-graders is 2:3.
Here's how to solve this step-by-step:
1. **Set up the ratios using variables:**
- Let the number of sixth-graders be \( 4x \).
- Hence, the number of fifth-graders is \( 5x \) (since the ratio is 5:4).
2. **Account for the additional 16 fifth-graders:**
\[
5x = 4x + 16
\]
Solve for \( x \):
\[
x = 16
\]
3. **Calculate the actual number of fifth and sixth graders:**
- Sixth-graders: \( 4x = 4 \cdot 16 = 64 \)
- Fifth-graders: \( 5x = 5 \cdot 16 = 80 \)
4. **Use the second ratio to find the number of seventh-graders:**
- The ratio of sixth-graders to seventh-graders is 2:3.
- If the number of sixth-graders is 64 (which is \( 2y \)), then the number of seventh-graders is \( 3y \).
- Setting \( 2y = 64 \), we get \( y = 32 \).
Number of seventh-graders:
\[
3y = 3 \cdot 32 = 96
\]
5. **Calculate the mean number of students:**
- Total number of students: \( 80 + 64 + 96 =](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fd0ba01ff-d830-49b1-ab72-2b4d49e145df%2Fec3c2c27-0352-4786-ad9d-c8e943537f52%2Fumfncy_processed.png&w=3840&q=75)
Transcribed Image Text:### Problem Statement:
**In Lee Middle School, the ratio of the number of fifth-graders to the number of sixth-graders is 5 to 4, and there are 16 more fifth-graders. If the ratio of the number of sixth-graders to the number of seventh-graders is 2 to 3, what is the mean number of students in the three grades?**
---
**Your Answer:**
[Text Box for User Input]
---
### Explanation:
In this problem, we need to find the mean number of students in the fifth, sixth, and seventh grades given the following ratios and information:
1. The ratio of fifth-graders to sixth-graders is 5:4.
2. There are 16 more fifth-graders than sixth-graders.
3. The ratio of sixth-graders to seventh-graders is 2:3.
Here's how to solve this step-by-step:
1. **Set up the ratios using variables:**
- Let the number of sixth-graders be \( 4x \).
- Hence, the number of fifth-graders is \( 5x \) (since the ratio is 5:4).
2. **Account for the additional 16 fifth-graders:**
\[
5x = 4x + 16
\]
Solve for \( x \):
\[
x = 16
\]
3. **Calculate the actual number of fifth and sixth graders:**
- Sixth-graders: \( 4x = 4 \cdot 16 = 64 \)
- Fifth-graders: \( 5x = 5 \cdot 16 = 80 \)
4. **Use the second ratio to find the number of seventh-graders:**
- The ratio of sixth-graders to seventh-graders is 2:3.
- If the number of sixth-graders is 64 (which is \( 2y \)), then the number of seventh-graders is \( 3y \).
- Setting \( 2y = 64 \), we get \( y = 32 \).
Number of seventh-graders:
\[
3y = 3 \cdot 32 = 96
\]
5. **Calculate the mean number of students:**
- Total number of students: \( 80 + 64 + 96 =
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