For her phone service, Lucy pays a monthly fee of $18, and she pays an additional $0.05 per minute of use. The least she has bee
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Answer:
325
Step-by-step explanation:
You must have heard about Arithmetic Progressions (AP)
Arithmetic progressions are a series of numbers such that every successive number is the sum of a constant number and the previous number.
Our very own counting numbers form AP
For example :-
2 = 1 + <u>1</u>
3 = 2 + <u>1</u>
4 = 3 + <u>1</u>
The number in bold (1) is that constant number which is added to a number to form its successive number.
To find the sum of series forming AP, we use the formula :-
here,
- n is the number of terms
- a is the first number of the series
- an is the last number of the series
So we'll use all this information to find the sum of continuous numbers from 1 to 25 where 1 is the first term(a) and 25 is the last(an).
and n is 25
So, the value of S comes out to be 325.