math help

[Guest]

1.

The average (arithmetic mean) length of 5 chains is 13 inches. If a 7 inch chain is added, the average length of the 6 chains is s inches. what is the value of s? Answer 12in

I did 5=13
6=s

and I don't know what else to do....

2.The price of a certain item is p dollars. A sales tax of 6% of the price of the item is added to the price to obtain the final cost. If p is an integer, then the final cost, in dollars, is p times what number?

I go p * .06

but the CORRECT answer is 1.06, where did the 1 come from?

 

[rahidz2003]

For number 1:

Arithmetic mean = (total)/(number of items)

13 inches = (total)/(5)

So, the total length of the 5 chains is 65 inches.

Adding 7 more inches would increase the total to 72 inches, and increase the number of items from 5 to 6.

Applying the same deifinition of arithmetic mean,

New arithmetic mean = (72 inches)/(6)

New arithmetic mean = 12 inches