To find out how many extra cups of flour John put in, we need to subtract the correct amount of flour required (3 3/10 cups) from the amount he actually added (3 5/8 cups).
First, we should convert both mixed numbers into improper fractions:
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Convert \(3 \frac{3}{10}\): \[ 3 \frac{3}{10} = \frac{3 \cdot 10 + 3}{10} = \frac{30 + 3}{10} = \frac{33}{10} \]
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Convert \(3 \frac{5}{8}\): \[ 3 \frac{5}{8} = \frac{3 \cdot 8 + 5}{8} = \frac{24 + 5}{8} = \frac{29}{8} \]
Now we need to find \( \frac{29}{8} - \frac{33}{10} \). To do this, we need a common denominator. The least common multiple of 8 and 10 is 40.
Next, we will convert both fractions to have a denominator of 40:
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Convert \( \frac{29}{8} \) to a denominator of 40: \[ \frac{29}{8} = \frac{29 \cdot 5}{8 \cdot 5} = \frac{145}{40} \]
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Convert \( \frac{33}{10} \) to a denominator of 40: \[ \frac{33}{10} = \frac{33 \cdot 4}{10 \cdot 4} = \frac{132}{40} \]
Now we can subtract the two fractions: \[ \frac{145}{40} - \frac{132}{40} = \frac{145 - 132}{40} = \frac{13}{40} \]
Thus, John put in an extra \( \frac{13}{40} \) cups of flour.
To express this as a decimal for clarity: \[ \frac{13}{40} = 0.325 \]
Therefore, the answer is that John put in an extra \( \frac{13}{40} \) cups of flour or 0.325 cups.
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