Aquart is what fraction of a half dollar

What is the standard deviation of the following data set rounded to the nearest tenth? 3, 17, 18, 15, 12, 21, 9

On a piece of paper graph f(x)=5•(0.4)^x

The average human heart beats 1.15 \cdot 10^51.15⋅10 5 1, point, 15, dot, 10, start superscript, 5, end superscript times per day. there are 3.65 \cdot 10^23.65⋅10 2 3, point, 65, dot, 10, start superscript, 2, end superscript days in one year. how many times does the heart beat in one year? write your answer in scientific notation, and round to one decimal place.