Question

Alba worked for 6 hr 45 min at $7.90 per hour. What numbers could she use to estimate how much money she earned? Estimate the amount she earned, and the state whether you think the exact amount is a little more or a little less than your estimate.

Answer 1

Answer:

• $52
• this estimate is a little low

Explanation:

a) I might choose 6 1/2 hours and $8 per hour, so the estimated earnings would be ...

  6(8) +(1/2)(8) = 52 dollars . . . . estimated earnings

These values are purposely chosen so that one is a little high and the other is a little low, hopefully producing a closer estimate than if both numbers were high (as 7 hours, $8, for example).

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b) Using 800 instead of 790 means the pay estimate is about 1/80 = 1.25% high.

Using 6 1/2 instead of 6 3/4 means the hours estimate is about 1/27 ≈ 3.7% low.

So, we expect the product of these values to be slightly low, perhaps by about 2.5%.

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Comment on estimating

If you can estimate the error in the estimate with some reasonable accuracy, you can use that to adjust the estimate to a pretty close value.