Question

Find the number of terms in the series 15, 20, 25,95.​

Answer 1

Step-by-step explanation:

Explanation:

Notice that if we match up the first and last pairs in the sequence, we always have a pair that adds to

55 :5,10,15,20,25,30,35,40,45,50

We see that:

5+50=55−−

10+45=55−−

15+40=55−−

20+35=55−−

25+30=55−−

Thus, the sum of the entire sequence is just

5 groupings of

55 , which is 5×55=275

.