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Zorluk: OrtaFractions, Decimals, Percentages, and Approximations

A rectangular lawn was measured to have a length of 15.0 m15.0\text{ m} and a width of 8.0 m8.0\text{ m}. If the actual length of the lawn is 16.0 m16.0\text{ m} and the measured width is exact, what is the percentage error in the calculated area of the lawn?

Cevap: 6.25 %

Cevap

The percentage error in the calculated area is 6.25%6.25\%.
The actual area of the lawn is 16.0 m×8.0 m=128 m216.0\text{ m} \times 8.0\text{ m} = 128\text{ m}^2, while the measured area is 15.0 m×8.0 m=120 m215.0\text{ m} \times 8.0\text{ m} = 120\text{ m}^2. The error is 128120=8 m2128 - 120 = 8\text{ m}^2. Expressed as a percentage of the actual area, 8128×100%=6.25%\frac{8}{128} \times 100\% = 6.25\%.

Adım Adım Çözüm

1
Calculate the measured area of the lawn using the measured length and width
Measured Area=15.0 m×8.0 m=120 m2\text{Measured Area} = 15.0\text{ m} \times 8.0\text{ m} = 120\text{ m}^2
Area of a rectangle is length multiplied by width.
2
Calculate the true (actual) area of the lawn using the actual length and exact width
Actual Area=16.0 m×8.0 m=128 m2\text{Actual Area} = 16.0\text{ m} \times 8.0\text{ m} = 128\text{ m}^2
The actual dimensions determine the true surface area.
3
Determine the magnitude of the error in area
Error=128 m2120 m2=8 m2\text{Error} = |128\text{ m}^2 - 120\text{ m}^2| = 8\text{ m}^2
Error is defined as the absolute difference between actual and measured values.
4
Compute the percentage error relative to the actual area
Percentage Error=8128×100%=6.25%\text{Percentage Error} = \frac{8}{128} \times 100\% = 6.25\%
Percentage error is always calculated as ErrorActual Value×100%\frac{\text{Error}}{\text{Actual Value}} \times 100\%.

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