In the 1900s, the life expectancy of a human in the United States was 50 years. The life expectancy of a human now is 78 years. What is the percentage change in the life expectancy of a human in the United States?

There would be a 56% increase

Step-by-step explanation:

We need to find the amount of change before we can find the percent of change. We'll take the greater value, 78, and subtract the lesser value, 50. 78 - 50 = 28. We then take this amount of change and put it over the original amount, Percent of change = Amount of change/ original amount or for this problem, 28/50. We then use that as a division equation for 28 divided by 50. 28 divided by 50 = 0.56. Finally we move the decimal to the right two times and we can then find the percentage increase.

ratio is 2 : 9

the answer is three

13.5 : 3