Answer:
144°
Step-by-step explanation:
step 1
Find the measure of the central angle of the regular pentagon
Divide 360 degrees by 5 (the number of sides)
Let
c----> the center of the pentagon
we know that
m∠ECA=72°
m∠ACB=72°
therefore
m∠ECB=m∠ECA+m∠ACB
substitute the values
m∠ECB=72°+72°=144°
The measure of angle ECB is equal to the degrees that the pentagon rotate
We want to find the value that makes
To find it we must look at the standard normal table, using the complementary cumulative table we find that
Then, using the z-score we can find the minimum score needed, remember that
Where
σ = standard deviation
μ = mean
And in our example, x = minimum score needed, therefore
Rounding to the nearest integer the minimum score needed is 568, if you get 568 you are at the top 20.1%.