To identify Camillo's error, let's break down the calculations he made based on the information provided:
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Determine the unit price of jelly: Given that 48 ounces of jelly costs 3 dollars and 84 cents (which is $3.84), we can first calculate the cost per ounce: \[ \text{Cost per ounce} = \frac{3.84}{48} = 0.08 \text{ (or 8 cents per ounce)} \]
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Calculate the total cost for 2,400 ounces: If the cost per ounce is $0.08, we multiply this by the total amount of jelly (2,400 ounces): \[ \text{Total cost} = 2,400 \times 0.08 = 192 \text{ dollars} \]
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Analyzing Camillo's calculations: According to the information provided, Camillo calculated a unit price of $13.79 and then multiplied by 2,400: \[ 13.79 \times 2,400 = 33,096 \text{ dollars} \] This figure is incorrect based on the correct cost per ounce of $0.08.
Now, evaluating the possible errors suggested in the options:
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He placed the decimal point incorrectly when dividing: This is likely true since he incorrectly determined the unit price.
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He placed the decimal point incorrectly when multiplying: This is not the main issue. The error appears to originate from how he calculated the unit price, not from multiplication.
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He wrote the rate incorrectly: This is also accurate; he calculated the cost per ounce incorrectly.
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He did not make an error: This is false, as his calculation of the cost for 2,400 ounces is incorrect.
From the evaluation, the most credible errors are the first and third options:
- He placed the decimal point incorrectly when dividing (leading to the incorrect unit price).
- He wrote the rate incorrectly.
Given the context that there was a miscalculation of the unit price, it is likely that the more direct answer is that he wrote the rate incorrectly (which stems from the decimal point error when calculating the unit price).
Final conclusion: He wrote the rate incorrectly.