Answer:
a) <em>Z-score = 0.75</em>
b) <em>Z-score = -32.833</em>
Step-by-step explanation:
<u><em>Step(i):-</em></u>
Given that mean of the Population = 33
Given a standard deviation of the Population = 12
Let 'X' be a random variable in a normal distribution
Let 'X' = 42
<u><em>Step(ii):-</em></u>
<em> </em>
<em></em>
<em> </em>
<em></em>
<u><em>Step(iii):-</em></u>
<em>Given that mean of the Population = 89</em>
Given a standard deviation of the Population = 1
Let 'X' be a random variable in a normal distribution
Let 'X⁻ = 82
<em> </em>
<em></em>
<em> </em>
<em></em>
<em>Z-score = -32.833</em>
<em></em>
Answer:165
Step-by-step explanation:
6•26 = 156. 156+9=165
Answer:
The range for boys is 0-12 and the mean is 5.1
The range for girls is 2-8 and the mean is 5.3
Step-by-step explanation:
Answer:
Bobby around 131 minutes and Billy around 111 minutes
Step-by-step explanation:
To solve the problem it is important to raise equations regarding what happens.
They tell us that Billy (Bi) and Bobby (Bo) can mow the lawn in 60 minutes. That is to say that what they prune in a minute is giving as follows:
1 / Bo + 1 / Bi = 1/60 (1)
They say Billy could mow the lawn only in 20 minutes less than it would take Bobby, therefore
1 / Bi = 1 / (Bo-20) (2)
Replacing (2) in (1) we have:
1 / Bo + 1 / (Bo-20) = 1/60
Resolving
(Bo - 20 + B0) / (Bo * (Bo-20) = 1/60
120 * Bo - 1200 = Bo ^ 2 - 20Bo
Rearranging:
Bo ^ 2 - 140Bo -1200 = 0
Now applying the general equation
Bo = 130.82 or Bo = 9.17, <em>this last value cannot be because Billy took 20 minutes less and neither can he prune faster than the two together</em>, therefore Bobby only takes around 131 minutes and Billy around 111 minutes
Checking with equation 1:
1/131 +1/111 = ~ 1/60
Answer:
The interval [32.6 cm, 45.8 cm]
Step-by-step explanation:
According with the <em>68–95–99.7 rule for the Normal distribution:</em> If
is the mean of the distribution and s the standard deviation, around 68% of the data must fall in the interval
![\large [\bar x - s, \bar x +s]](https://tex.z-dn.net/?f=%5Clarge%20%5B%5Cbar%20x%20-%20s%2C%20%5Cbar%20x%20%2Bs%5D)
around 95% of the data must fall in the interval
around 99.7% of the data must fall in the interval
![\large [\bar x -3s, \bar x +3s]](https://tex.z-dn.net/?f=%5Clarge%20%5B%5Cbar%20x%20-3s%2C%20%5Cbar%20x%20%2B3s%5D)
So, the range of lengths that covers almost all the data (99.7%) is the interval
[39.2 - 3*2.2, 39.2 + 3*2.2] = [32.6, 45.8]
<em>This means that if we measure the upper arm length of a male over 20 years old in the United States, the probability that the length is between 32.6 cm and 45.8 cm is 99.7%</em>