Find two numbers that round to 387.4 when rounded to the nearest ten

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

You have a 32-foot fence around a square garden. there are 4 equal sections. you paint 13 of one section of the fence. what fraction of the fence did you paint? you have a 32-foot fence around a square garden. there are 4 equal sections. you paint 13 of one section of the fence. what fraction of the fence did you paint?

Prove that the value of the expression 7^8–7^7+7^6 is divisible by 43.