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:
Average speed is 37.35 mi/h
Step-by-step explanation:
given data
leave = 34 minutes before
church distance = 12.0 miles
average speed first 17 minutes = 5.0 mi/h
solution
so we find Total distance travel in first 17 minutes = speed × time
Total distance travel in first 17 minutes = 5 × 
Total distance travel in first 17 minutes = 1.416 mi
and
Distance Remaining = 12 - 1.416 = 10.584 mi
Time Remaining = 34 - 17 min = 17 min
so
remaining distance Average speed =
Average speed =
Average speed is 37.35 mi/h
75 бутеров!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1.75 hours, add them up and divide by two and you get your answer
1/10 of .9 is the same as dividing .9 by 10.
.90 / 10 = .09
.09 is the answer