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11-54.

Daylight Saving Time was adopted in the U.S. in $1918$. During the oil crisis of the $1970$s, the Department of Transportation found that daylight saving time decreased national energy usage by about $1$ percent compared with standard time. Since then, energy use in the U.S. has changed and daylight saving time has been extended. In $2007$ a group of researchers found that daylight saving time decreased national energy usage by $0.2\%$ with a margin or error of $1.5\%$. If a $1\%$ decrease in energy use will save the state of Indiana $\9$ million, what conclusion(s) can you draw from the $2007$ study in relation to the state of Indiana?

Energy usage can be expected to change in Indiana by $0.2\%\pm1.5\%$.
What range of percentages is this? Use this range to calculate the cost/savings to the state.