Answer:
The new mean for the exam scores is 51
Step-by-step explanation:
the mean can be calculated using the formula
mean of scores = 
before the 20 points was added, the mean of the score was = 50.
Inserting this into the formula, we have:
50 = 
from this, we can compute the sum total of the scores as
sum total = 50 × 20 = 1000
when the extra 20 marks is added, the sum of the entire scores will be changed to 1000 + 20 = 1020.
Hence the new mean will be computed as (New Sum total of scores / Number of students)
=
= 51.
∴ The new mean of the scores is = 51
X=-2
You can also check by plugging -2 in for x. Here is a picture. Please notify me if I made an error!
1/2bh
1/2b4 = 18
b4= 36
b= 9 yards