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Minimum and maximum area

The rectangle below is labeled with its measured dimensions. Taking measurement error into account, what are the minimum and maximum possible areas?

• To find the minimum possible area, subtract the greatest possible error from each measurement before calculating.
• To find the maximum possible area, add the greatest possible error to each measurement before calculating.

You want to find the minimum and maximum area, taking measurement error into account.

First find the greatest possible error. Each measurement was made to the nearest whole mile, so the greatest possible error is half of 1 mile, which is 0.5 miles.

To find the maximum possible area, add the greatest possible error to each measurement, then multiply.

 Amax = LmaxWmax = (7 + 0.5)(4 + 0.5) Add the greatest possible error, 0.5 = (7.5)(4.5) = 33.75

To find the minimum possible area, subtract the greatest possible error from each measurement, then multiply.

 Amin = LminWmin = (7 – 0.5)(4 – 0.5) Subtract the greatest possible error, 0.5 = (6.5)(3.5) = 22.75

The minimum possible area is 22.75 square miles.

The maximum possible area is 33.75 square miles.

The rectangle below is labeled with its measured dimensions. Taking measurement error into account, what are the minimum and maximum possible areas?

 21 mm 18 mm

The maximum possible area is mm2
The minimum possible area is mm2