The U.S. Strategic Oil Reserve is a government-owned stockpile...

Question

The U.S. Strategic Oil Reserve is a government-owned stockpile of crude oil. It was established after the oil embargo in the mid-1970s and is meant to serve as a national defense fuel reserve, as well as to offset reductions in commercial oil supplies that would threaten the U.S. economy. The graphic depicts oil reserves in 1977 and 2018.

b. The United States imported approximately 10.14 million barrels of oil per day in 2018. At that rate, assuming no change in U.S. oil production, how long would the U.S. strategic oil reserve last if no oil were imported?

Two oil barrels comparing U.S. Strategic Oil Reserves: 7.5 million barrels in 1977 and 652.6 million in 2018.

Accepted Answer

Welcome back, everyone. Country X holds a strategic oil stockpile of 1200 million barrels. The country imports approximately 15,500,000 barrels per day. At that import rate and assuming no change in domestic production, how long would the stockpile last if imports stopped? Report your answer in days and in months using 30 days per month. For this problem we want to calculate time. We're going to begin with the number of barrels. In particular, we have 1 billion. 200 million barrels to begin with. To calculate the number of days we're going to use conversion factors. The only conversion factor. Given to us initially is 15,500,000 barrels per day. Now, whenever we use conversion factors, we place the unit that we want to cancel out in the denominator. So we're going to add barrels because we want to cancel out barrels and we want to get the days, right? So essentially we're going to put these in the numerator because the desired quantity goes into the numerator. Notice that we can cancel out barrels and we're going to get these. And now we're going to fill out our conversion factor. We know that we have 15,500,000. barrels per day. So for the number of days we're going to use 1 per one day. And now we want to multiply by 1 and divide by 15,500,000 starting with 1 billion 200 million. Performing the calculation, we're going to report our answer to two significant figures. And the answer would be 77 days. Now, what about the number of months? We can repeat the same process, starting with 1 billion. 200 million. Barrels We are first converting it. 2 days. Using the conversion factor one day. Corresponds to. 15 1,500,000 barrels. So, this allows us to cancel out the barrels and get days. We're not going to use 77 because it is a rounded value, right? We're going to repeat the whole calculation, and from here that we have days, we want to cancel our days. And get months. So we add months in the numerator and days in the denominator so that we can cancel out days. Since now these belong to opposite sides of the two conversion factors. According to the context of the problem, we're going to use 1 month is equivalent to 30 days. So we want to divide our answer, which is approximately 77 by 30. Performing the calculation, we get 2.6 months. Those will be our final answers. Let's label them 77 days. Or 2.6 months. Thank you for watching.

Key Concepts

Unit Conversion and Scale

Rate and Time Relationship

Interpretation of Graphical Data

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