3 ¾
Step-by-step explanation:
-3½+4¼=-²/⁴ +17/4=15/4
3¾
Answer:
P (z for -2.23) is -0.9871
Step-by-step explanation:
Given data
mean life x = 753 hours
sample n = 28
mean y = 726
standard deviation SD = 64 hours
to find out
check to have enough evidence to reject his claim
solution
we know that given mean is x ≥ 753
we found mean = 726
so difference = y - x = 726 - 753 = -27
and we know σ = SD/√n = 64 / √28 = 12.094896
Z = y - x / σ
Z = -27 / 12.09
Z = -2.23
so probability value
P (z for -2.23) is -0.9871
so z value is less than alpha = 0.05
so reject
so this is enough evidence to reject his claim
Answer:
Tasha should mix 25 liters of 20% solution and 50 liters of 50%.
Step-by-step explanation:
Let x liters be the amount of 20% solution and y liters be the amount of 50% solution Tasha takes.
1. Tasha needs 75 liters of a 40% solution of alcohol. Then
x + y = 75
2. There are
- liters of alcohol in x l of 20% solution
- liters of alcohol in 50% solution
- liters of alcohol in 75 liters of 40% solution
In total, of alcohol that is 30 l, so
0.2x + 0.5y = 30
3. Solve the system of two equations:
From the first equation:
Substitute it into the second equation
Tasha should mix 25 liters of 20% solution and 50 liters of 50%.
The valid prediction for the mean of the population possible using these samples is C. Yes, the variation of the sample means is small
<h3>What is a sample mean?</h3>
It should be noted that a sample mean is an average of a set of data . Also, the sample mean can be used to calculate the standard deviation, central tendency, and the variance of a data set.
The sample mean can be applied to a variety of uses, including calculating population averages.
Here, the sample variance is a measure of the degree to which the numbers in a list are spread out. Here, the numbers given are close to each other.
If the numbers in a list are all close to the expected values, the variance will be small and if they are far away, the variance will be large.
Therefore, the correct option is C.
Learn more about mean on:
brainly.com/question/1136789
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Answer:
x = 1/3 ln(2)
Step-by-step explanation:
e^(3x)+6=8
Subtract 6 from each side
e^(3x)+6-6=8-6
e^(3x) = 2
Take the natural log of each side
ln (e ^3x) = ln (2)
3x = ln(2)
Divide by 3
3x/3 = 1/3 ln(2)
x = 1/3 ln(2)