Answer:
Percentage of scores that fall between 70 and 80 = 24.34%
Step-by-step explanation:
We are given a test with a population mean of 75 and standard deviation equal to 16.
Let X = Percentage of scores
Since, X ~ N(
)
The z probability is given by;
Z =
~ N(0,1) where,
= 75 and
= 16
So, P(70 < X < 80) = P(X < 80) - P(X <= 70)
P(X < 80) = P(
<
) = P(Z < 0.31) = 0.62172
P(X <= 70) = P(
<
) = P(Z < -0.31) = 1 - P(Z <= 0.31)
= 1 - 0.62172 = 0.37828
Therefore, P(70 < X < 80) = 0.62172 - 0.37828 = 0.24344 or 24.34%
249 km in 3 hours are 83 km in 1 hours
249 : 3 = 83 Km
If the '7t' is supposed to be '7y', then the answer is below
(4y+8)-(7y-12)=11
distribute the negative into the second parenthesis
4y+8-7y+12=11
combine like terms
-3y+20=11
subtract the 20 from both sides
-3y=-9
divide by -3 on both sides
y=3
if it is supposed to be '7t', I'm not sure if there's enough information