Question

In 1950 use of coal is 114.6 million tons. It decreased by 6.6% per year since then. Estimate the amount of coal used in 2010. Round to the nearest tenth of a million tons...(is there a formula?)

Answer 1

The grizzly bear population in Yellowstone national park in 1970 was about 270. Over the next 35 years, it increased by about 115%. What was the population in 2005?

Find the amount of change
1.15×270=310.5 find 115% of 270. Write 115 as a decimal
~311 Round to the nearest whole number
Find the new amount
New amount = original amount + amount of change
= 270 + 311 substitute values
= 581
This is an example this should help if you could reverse it somehow because this was for percentage increase and not decrease.