Question

I did this problem, but is there a simpler way of doing it?A person hired a firm to build a CB tower. The firm charges $100 for labor for the first 10 feet. After that, the cost of the labor for each succeeding 10 feet is $25 more than the proceeding 10 feet. That is, the next 10 feet will cost $125; the next 10 feet will cost $150, etc. How much will it cost to build a 90-foot tower? 10 feet = $100 for a total of 10 feet 10 feet =$125 for a total of 20 feet 10 feet = $150 for a total of 30 feet 10 feet = $175 for a total of 40 feet 10 feet = $200 for a total of 50 feet 10 feet = $225 for a to

Answer 1

100 + 25x

x represents 10 feet

to find 90 feet, you take 100 and add 25(9)

that would be $325

Answer 2

A person hired a firm to build a CB tower. The firm charges $100 for labor for the first 10 feet. After that, the cost of the labor for each succeeding 10 feet is $25 more than the proceeding 10 feet. That is, the next 10 feet will cost $125; the next 10 feet will cost $150, etc. How much will it cost to build a 90-foot tower?
10 feet = $100 for a total of 10 feet 10 feet =$125 for a total of 20 feet
10 feet = $150 for a total of 30 feet 10 feet = $175 for a total of 40 feet
10 feet = $200 for a total of 50 feet 10 feet = $225 for a total of 60 feet
10 feet = $250 for a total of 70 feet 10 feet = $275 for a total of 80 feet
10 feet = $300 for a total of 90 feet
The sum up all these numbers, $100+$125+$150+…..+$300 = $1800
This what I did and got a different answer

Answer 3

Just need to know if there is a easier way to write it

Answer 4

no, you wouldn't add them, and you forgot to add in the 90 feet would be 325. My formula is correct.

Answer 5

wait a sec. u were right the second time......... http://answers.yahoo.com/question/index?qid=20110529092846AASquuc

Answer 6

It did not let me post the whole question the first time

Answer 7

oh, that's fine :)

Answer 8

this is an arithmetic sequence whose first term is 100, the second term is 125, the third term is 150 and so on and there are 9 terms.
The formula for the sum of an arithmetic sequence is
\[s _{n}=n(a _{1}+a _{n})/2\] where n is the number of terms, a1 is the first term and an is the nth term. In this problem the first term is 200 and the 9th term is 300.

So we have: