The mean of the data set is 40 and one standard deviation is 5. About what percent of the numbers fall between 35 and 50?
1 answer:
Answer:
The correct option is D. 81.8%
Step-by-step explanation:
Mean of the data set is given to be 40
⇒ μ = 40
Standard deviation of the data set is given to be 5
⇒ σ = 5
Now we are supposed to find out what percent of the numbers fall between 35 and 50
Now for P(35 < x < 50) :
Substitute x = 35 ⇒ z = -1
Substitute x = 50 ⇒ z = 2
So, P(-1 < z < 2) = P(z < 2) - P(z < -1)
⇒ P(-1 < z < 2) = 0.9772 - 0.1587
⇒ P(-1 < z < 2) = 0.8185
⇒ P(-1 < z < 2) = 81.8%
Therefore, 81.8% percent of the numbers fall between 35 and 50
Hence, The correct option is D. 81.8%
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Answer:
1)
the mean rate of return is 17 %
the standard deviation of return is 17.06055
2)
the probability that Marvin's portfolio will make at least 20% over the next 12 months is 0.4325
Step-by-step explanation:
Given the data in the question;
1)
For the portfolio, the mean return and standard deviation are computed as follows;
Mean = Return = 0.65 × 10 + 0.35 × 30
= 6.5 + 10.5
= 17 %
Therefore, the mean rate of return is 17 %
Standard deviation will be;
σp = √( 0.65² × 15² + 0.35² × 40² )
= √( 0.4225 × 225 + 0.1225 × 1600 )
= √( 95.0625 + 196 )
= √291.0625
= 17.06055
Therefore, the standard deviation of return is 17.06055
2)
probability that Marvin's portfolio will make at least 20% over the next 12 months.
P( X > 20 )
we convert to a standard normal variable;
Z = )
Z = 0.17
from z table, p-value is;
p( X < 20 ) = 0.5675
P( X > 20 ) 1 - 0.5675 = 0.4325
Therefore, the probability that Marvin's portfolio will make at least 20% over the next 12 months is 0.4325