In 1950 the use of coal in the us was 114.6 million tons. the use of coal has decreased by 6.6% per year since then. estimate the amount of coal used in the us in 2010.

Amount of estimated coal that has been used in the year 2010 = 23.1 million tons

Step-by-step explanation:

In 1950 the use of coal in the us was 114.6 million tons

The use of coal has decreased by 6.6% per year since then

The time would be 2010 - 1950 = 60 years  

Let the estimate amount used in the year 2010

⇒ 114.6 = x(1 + 0.066 × 60)

⇒ 114.6 = x × 4.96

⇒ x = 23.1

Therefore, Amount of estimated coal that has been used in the year 2010 = 23.1 million tons

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step-by-step explanation:

circumference divided by 3.141592654 then timesthe radius twice