Answer:
n=-19
Step-by-step explanation:
-9+n/4=-7
Multiply 4 on both sides
-9+n=-28
Add 9 on both sides
n=-19
Given:
First term of an arithmetic sequence is 2.
Sum of first 15 terms = 292.5
To find:
The common difference.
Solution:
We have,
First term: 
Sum of first 15 terms: 
The formula of sum of first n terms of an AP is
![S_n=\dfrac{n}{2}[2a+(n-1)d]](https://tex.z-dn.net/?f=S_n%3D%5Cdfrac%7Bn%7D%7B2%7D%5B2a%2B%28n-1%29d%5D)
Where, a is first term and d is common difference.
Putting
, n=15 and a=2 in the above formula, we get
![292.5=\dfrac{15}{2}[2(2)+(15-1)d]](https://tex.z-dn.net/?f=292.5%3D%5Cdfrac%7B15%7D%7B2%7D%5B2%282%29%2B%2815-1%29d%5D)
![292.5=\dfrac{15}{2}[4+14d]](https://tex.z-dn.net/?f=292.5%3D%5Cdfrac%7B15%7D%7B2%7D%5B4%2B14d%5D)
![292.5=15[2+7d]](https://tex.z-dn.net/?f=292.5%3D15%5B2%2B7d%5D)
Divide both sides by 15.




Dividing both sides by 7, we get


Therefore, the common difference is 2.5.
Answer:
7/12
Step-by-step explanation:
7+5=12
12-5=7
7/12
<h2><u>
Answer with explanation</u>
:</h2>
Let
be the population mean.
As per given , we have

Since the alternative hypothesis is right-tailed , so the test is a right-tailed test.
Also, population standard deviation is given
, so we perform one-tailed z-test.
Test statistic : 
, where
= Population mean
= Population standard deviation
n= sample size
= Sample mean
For n= 18 ,
,
,
, we have

P-value (for right tailed test): P(z>2.12) = 1-P(z≤ 2.12) [∵ P(Z>z)=1-P(Z≤z)]\
=1- 0.0340=0.9660
Decision : Since P-value(0.9660) > Significance level (0.01), it means we are failed to reject the null hypothesis.
[We reject null hypothesis if p-value is larger than the significance level . ]
Conclusion : We do not have sufficient evidence to show that the goal is not being met at α = .01 .
Slope =(9+3)/(-2-4) = 12/-6 = -2
Y+3 = -2 (×-4) => y=-2×+5
D is the line asked
Slope: -1/3
D: y-6 = -1/3 (×-3) or y= -1/3× + 7