On April 20th, 2010, an explosion and fire on an oil rig operated by British Petroleum (BP) caused the worst oil spill in history. On May 20th, the Associated Press reported, “oil has been pouring into the Gulf from a blown-out undersea well at a rate of at least 210 ,000 gallons per day.” Unfortunately, this turned out to be a best-case estimate. On June 20th, 2010, Associated Press reported that a confidential memo by BP gave a worst-case estimate of 4.2 million gallons per day pouring into the ocean.

a. What is the difference in gallons per day between the worst- and best-case scenarios? Use scientific notation to express your answer.
the scientfic notation I got was 4.2*10^6 so I would use that to express the difference and put it over 2.1*10^5, but then I'm stuck. Help.

You just subtract them to get 3.99*10^6

To find the difference in gallons per day between the worst-case and best-case scenarios, we can subtract the best-case estimate from the worst-case estimate.

The worst-case estimate is 4.2 million gallons per day, which can be represented in scientific notation as 4.2 × 10^6.

The best-case estimate is 210,000 gallons per day, which can be represented as 2.1 × 10^5.

To subtract these two values, we need to ensure that both numbers have the same exponent. We can achieve this by converting the best-case estimate to scientific notation with the same exponent as the worst-case estimate.

2.1 × 10^5 can be rewritten as 0.21 × 10^6 (by moving the decimal point one place to the left). So, now we have:

Worst-case estimate: 4.2 × 10^6 gallons per day
Best-case estimate: 0.21 × 10^6 gallons per day

Subtracting these two values gives us:

(4.2 × 10^6) - (0.21 × 10^6) = (4.2 - 0.21) × 10^6 = 3.99 × 10^6

Therefore, the difference between the worst-case and best-case scenarios is 3.99 × 10^6 gallons per day, expressed in scientific notation.