If you can give me more information on this I could help you a bit more respond.
C should be your answer:))))
Answer:
a = 20
Step-by-step explanation:
The mean is calculated as
mean = 
=
= 
Then
= 27 ( multiply both sides by 5 to clear the fraction )
115 + a = 135 ( subtract 115 from both sides )
a = 20
0.9 x 10^4
Let’s break this down into steps.
So to start off with, you need to do 4.5/5 which = 0.9.
Now we can deal with the indices. 10^-3 / 10^-7 means we have to subtract them. Therefore, -3 - -7 = 4. Altogether, we have 0.9 x 10^4
The question states we should leave our answer in standard form.
So our answer is 0.9 x 10^4.