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Rates, SM-Bank 085 MC

The nutritional information on a breakfast cereal is shown below.

 

 
Kylie expends 1000 kJ of energy by rowing for 30 minutes.

If she consumes 100 grams of the cereal, approximately how long should she row to use up the energy it provides?

  1. 45 minutes
  2. 60 minutes
  3. 65 minutes
  4. 75 minutes
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\(D\)

Show Worked Solution

\(100\ \text{grams of cereal}\rightarrow 2460\ \text{kJ}\)

\(\text{Exercise required}\) \(=\dfrac{2460}{1000}\times 30\)
  \(\approx 2.5\times 30\)
  \(\approx 75\ \text{minutes}\)

 
\(\Rightarrow D\)

Rates, SM-Bank 084 MC

The nutritional information on a power bar is shown below.

 

 
Sandra expends 900 kJ of energy by running for 20 minutes.

If she consumes 100 grams of the power bar, approximately how long should she run to use up the energy it provides?
 

  1. 20 minutes
  2. 30 minutes
  3. 40 minutes
  4. 55 minutes
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\(C\)

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\(100\ \text{grams of power bar}\rightarrow 1810\ \text{kJ}\)

\(\text{Exercise required}\) \(=\dfrac{1810}{900}\times 20\)
  \(\approx 2\times 20\)
  \(\approx 40\ \text{minutes}\)

 
\(\Rightarrow C\)

Rates, SM-Bank 083 MC

The nutritional information on a breakfast cereal is shown below.

 

 

Anna expends 650 kJ of energy by swimming for 30 minutes.

If she consumes 100 grams of the cereal, approximately how long should she swim to use up the energy it provides?

  1. 30 minutes
  2. 45 minutes
  3. 60 minutes
  4. 75 minutes
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\(C\)

Show Worked Solution

\(100\ \text{grams of cereal}\rightarrow 1320\ \text{kJ}\)

\(\text{Exercise required}\) \(=\dfrac{1320}{650}\times 30\)
  \(\approx 2\times 30\)
  \(\approx 60\ \text{minutes}\)

 
\(\Rightarrow C\)

Rates, SM-Bank 082 MC

The nutritional information on a breakfast cereal is shown below.

 

 
Marjorie expends 1000 kJ of energy by jogging for 30 minutes.

If she consumes 100 grams of the cereal, approximately how long should she jog to use up the energy it provides?

  1. 30 minutes
  2. 40 minutes
  3. 60 minutes
  4. 80 minutes
Show Answers Only

\(B\)

Show Worked Solution

\(100\ \text{grams of cereal}\rightarrow 1320\ \text{kJ}\)

\(\text{Exercise required}\) \(=\dfrac{1320}{1000}\times 30\)
  \(\approx 1.3\times 30\)
  \(\approx 40\ \text{minutes}\)

 
\(\Rightarrow B\)

Rates, SM-Bank 018

A solar panel grid on a school roof produces an average of 8.6 kWh of energy per day.

How much energy will the grid produce for the school on average over 7 days?  (2marks)

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\(60.2\ \text{kWh}\)

Show Worked Solution

\(\text{One multiplication strategy:}\)

\(7\times 8=56\)

\(7\times 0.6 = 4.2\)

\(7\times 8.6 = 56+4.2=60.2\)
 

\(\therefore\ \text{It produces 60.2 kWh over 7 days.}\)