Answer:
628
Step-by-step explanation:
We have the standard deviation of the sample, so we use the t-distribution to solve this question.
The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So
df = 12 - 1 = 11
95% confidence interval
Now, we have to find a value of T, which is found looking at the t table, with 11 degrees of freedom(y-axis) and a confidence level of 
. So we have T = 2.2
The margin of error is:
In which s is the standard deviation of the sample and n is the size of the sample.
The lower end of the interval is the sample mean subtracted by M. So it is 665 - 37 = 628 hours.
The answer is 628
Answer:
The probability that the stock will sell for $85 or less in a year's time is 0.10.
Step-by-step explanation:
Let <em>X</em> = stock's price during the next year.
The random variable <em>X</em> follows a normal distribution with mean, <em>μ</em> = $100 + $10 = $110 and standard deviation, <em>σ</em> = $20.
To compute the probability of a normally distributed random variable we first need to compute the <em>z</em>-score for the given value of the random variable.
The formula to compute the <em>z</em>-score is:
Compute the probability that the stock will sell for $85 or less in a year's time as follows:
Apply continuity correction:
P (X ≤ 85) = P (X < 85 - 0.50)
= P (X < 84.50)
*Use a <em>z</em>-table for the probability.
Thus, the probability that the stock will sell for $85 or less in a year's time is 0.10.
Answer:
a
Step-by-step explanation:
Answer:
You have to plot 10 on number line
Just Move 10 units Forward From O(zero or origin) to locate it
Im not sure but...
(x+21) + (2x+9)=90
x+21+2x+9 = 90
3x+30 = 90
3x = 60
x = 20
