To find the total number of seventh graders who prefer bananas, we will use the information provided in the two-way table. We know:
- Total number of seventh graders: 120
- Seventh graders who prefer apples: 41
- Total number of apples preferred by both grades: 75
First, let's calculate the number of seventh graders who prefer bananas and oranges:
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Find the number of seventh graders who prefer apples, bananas, and oranges.
- Let \( b \) be the number of seventh graders who prefer bananas.
- Let \( o \) be the number of seventh graders who prefer oranges.
From the total for seventh graders:
\[ 41 + b + o = 120 \]
This simplifies to:
\[ b + o = 120 - 41 = 79 \quad \text{(1)} \]
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Looking at the total preferences for apples:
- The total number of apples is 75, so for eighth graders, we can calculate their preference as follows:
- Let \( x \) be the number of eighth graders who prefer apples.
Thus,
\[ 41 + x = 75 \]
Solving for \( x \):
\[ x = 75 - 41 = 34 \]
- The total number of apples is 75, so for eighth graders, we can calculate their preference as follows:
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Now, we have the information for eighth graders:
- Apples: 34
- Bananas: 32
- Oranges: 45
Total for eighth graders:
\[ 34 + 32 + 45 = 111 \]
We validate how many seventh graders eat bananas and oranges:
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Total bananas across both grades is the count of bananas preferred by both grades which we have as 32 from eighth graders. So the total number for bananas is \( b + 32 \).
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Looking at the total preferences for bananas:
\[ b + 32 \quad \text{(total bananas)} \]
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The total number of bananas preferred is not provided. However, since seventh graders total their fruit preference to 79, we can revise the known from their total:
Using equation (1):
\[ b + o = 79 \]
Now let's calculate using the total oranges:
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The total oranges were provided across both grades, 72:
The number of eighth graders' oranges is 45, hence seventh graders:
\[ o = 72 - 45 = 27 \]
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Substitute \( o = 27 \) back into equation (1):
\[ b + 27 = 79 \]
Solving for \( b \):
\[ b = 79 - 27 = 52 \]
Thus, the total number of seventh graders who prefer bananas is \( \boxed{52} \).