Sarah plans to buy books at a book fair she thinks she will need $30 to purchase the books she only spends $19.75. Find the percent error in her prediction round your answer to the nearest whole number.

To find the percent error, we need to calculate the difference between the predicted amount ($30) and the actual amount spent ($19.75), and then express that difference as a percentage of the predicted amount.

The difference is $30 - $19.75 = $10.25.

To express this as a percentage of the predicted amount, we divide by $30 and multiply by 100:
($10.25 / $30) * 100 = 34.17

Rounding to the nearest whole number, the percent error is 34%.

To find the percent error in Sarah's prediction, you need to calculate the difference between her predicted cost and the actual cost, and then express that difference as a percentage of her predicted cost.

First, subtract the actual cost from Sarah's prediction:
$30 - $19.75 = $10.25

Next, divide the difference by her predicted cost and multiply by 100 to get the percentage:
($10.25 / $30) * 100 = 34.17

Finally, round the percentage to the nearest whole number:
34.17 ≈ 34

Therefore, the percent error in Sarah's prediction is approximately 34%.