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Zorluk: KolayFractions, Decimals, and Percents Arithmetic

In January, electricity comprised 0.450.45 of a facility's total energy consumption. In February, electricity comprised 35\frac{3}{5} of its total energy consumption. If the facility's total energy consumption was constant at 1,2001,200 kilowatt-hours in each of the two months, by how many kilowatt-hours did its electricity consumption increase from January to February?

  1. A
    150150 kilowatt-hours
  2. 180180 kilowatt-hoursCevap
  3. C
    270270 kilowatt-hours
  4. D
    540540 kilowatt-hours
  5. E
    720720 kilowatt-hours

Cevap

The electricity consumption increased by 180180 kilowatt-hours from January to February.
The correct answer of 180180 kilowatt-hours is found by converting both fractions and decimals into comparable parts of the 1,2001,200 kilowatt-hour base. January electricity usage is 0.45×1,200=5400.45 \times 1,200 = 540 kWh. February electricity usage is 35×1,200=720\frac{3}{5} \times 1,200 = 720 kWh. The difference is 720−540=180720 - 540 = 180 kWh. Alternatively, subtracting the proportions first gives 35−0.45=0.60−0.45=0.15\frac{3}{5} - 0.45 = 0.60 - 0.45 = 0.15, and 0.15×1,200=1800.15 \times 1,200 = 180 kWh.

Adım Adım Çözüm

1
Calculate the January electricity consumption
0.45×1,200=5400.45 \times 1,200 = 540 kilowatt-hours
Electricity represented 0.450.45 of the 1,2001,200 kilowatt-hour total.
2
Calculate the February electricity consumption
35×1,200=0.60×1,200=720\frac{3}{5} \times 1,200 = 0.60 \times 1,200 = 720 kilowatt-hours
Electricity represented 35\frac{3}{5} (or 0.600.60) of the 1,2001,200 kilowatt-hour total.
3
Find the difference between February and January consumption
720−540=180720 - 540 = 180 kilowatt-hours
Subtracting January usage from February usage yields the net increase.

Anahtar Kavram

Fraction and Decimal Conversions and Amount Computations
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Fractions, Decimals, and Percents Arithmetic

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