Question

21 and 22 refer to the following
renewable energy consumption
the bar graph above shows renewable energy consumption in quadrillions of british thermal units (btu) in the united states, by energy source, for several energy sources in the years 2000 and 2010.
21
in a scatter - plot of this data, where renewable energy consumption in the year 2000 is plotted along the x - axis and renewable energy consumption in the year 2010 is plotted along the y - axis for each of the given energy sources, how many data points would be above the line y = x?
a) 1
b) 2
c) 3
d) 4
22
of the following, which best approximates the percent decrease in consumption of wood power in the united states from 2000 to 2010?
a) 6%
b) 11%
c) 21%
d) 26%

Explanation:

Step1: Analyze scatter - plot condition

Points above $y = x$ mean consumption in 2010 is greater than in 2000.

Step2: Examine bar - graph data

For biofuels, 2010 consumption is greater than 2000. For geothermal, 2010 consumption is less. For hydroelectric, 2010 consumption is less. For wind, 2010 consumption is greater. For wood, 2010 consumption is less. So there are 2 data points (biofuels and wind) above $y = x$.

Step1: Recall percent - decrease formula

Percent decrease=$\frac{\text{Initial value}-\text{Final value}}{\text{Initial value}}\times100\%$. Let the consumption in 2000 be the initial value and in 2010 be the final value.

Step2: Estimate wood consumption values

From the bar - graph, consumption of wood in 2000 is about 2.00 quadrillion Btu and in 2010 is about 1.60 quadrillion Btu.

Step3: Calculate percent decrease

Percent decrease=$\frac{2.00 - 1.60}{2.00}\times100\%=\frac{0.40}{2.00}\times100\% = 20\%$. The closest option is 21%.

Answer:

B. 2