The sum

The sum of the first 10 members of the arithmetic sequence is 120. What will be the sum if the difference is reduced by 2?

Correct result:

s2 =  30

Solution:

s1=120 n=10  s1=a1+a2+a3+…+an  d2=d1−2  s1=10/2⋅ (a1+a1+9⋅ d1)=10⋅ a1+45⋅ d1=120 s2=10/2⋅ [a1+a1+9⋅ (d1−2)] s2=10⋅ a1+45⋅ d1−5⋅ 9⋅ 2  s2=s1−5⋅ 9⋅ 2=120−5⋅ 9⋅ 2=30

Try another example


We would be pleased if you find an error in the word problem, spelling mistakes, or inaccuracies and send it to us. Thank you!






Showing 0 comments:
avatar




Tips to related online calculators
Looking for help with calculating arithmetic mean?
Looking for a statistical calculator?

You need to know the following knowledge to solve this word math problem:


 
We encourage you to watch this tutorial video on this math problem: video1

Next similar math problems:

  • Here is
    calc Here is a data set (n=117) that has been sorted. 10.4 12.2 14.3 15.3 17.1 17.8 18 18.6 19.1 19.9 19.9 20.3 20.6 20.7 20.7 21.2 21.3 22 22.1 22.3 22.8 23 23 23.1 23.5 24.1 24.1 24.4 24.5 24.8 24.9 25.4 25.4 25.5 25.7 25.9 26 26.1 26.2 26.7 26.8 27.5 27.6 2
  • Finite arithmetic sequence
    seq_sum_1 How many numbers should be inserted between the numbers 1 and 25 so that all numbers create a finite arithmetic sequence and that the sum of all members of this group is 117?
  • Loan 5
    seq_sum Abdul takes a loan of 200000 from Ali and agrees to repay in number of instalment, each instalment begin with the 2nd exceeding the previous one by 1000, if the first instalment is 500, find how many instalment will be necessary to be wipe out the loan? C
  • Quiz or test
    test_2 I have a quiz with 20 questions. Each question has 4 multiple choice answers, A, B, C, D. THERE IS NO WAY TO KNOW THE CORRECT ANSWER OF ANY GIVEN QUESTION, but the answers are static, in that if the "correct" answer to #1 = C, then it will always be equal
  • Difference AP
    delta Calculate the difference of arithmetic progression if the sum of its first 19 members Sn = 8075 and the first member is a1 = 20
  • Octahedron - sum
    8sten On each wall of a regular octahedron is written one of the numbers 1, 2, 3, 4, 5, 6, 7 and 8, wherein on different sides are different numbers. For each wall John make the sum of the numbers written of three adjacent walls. Thus got eight sums, which also
  • Complaints
    statistics The table is given: days complaints 0-4 2 5-9 4 10-14 8 15-19 6 20-24 4 25-29 3 30-34 3 1.1 What percentage of complaints were resolved within 2weeks? 1.2 calculate the mean number of days to resolve these complaints. 1.3 calculate the modal number of day
  • 1 page
    books 1 page is torn from the book. The sum of the page numbers of all the remaining pages is 15,000. What numbers did the pages have on the page that was torn from the book?
  • Negative difference
    arithmet_seq Find four arithmetic progression members between 7 and -6.
  • Consecutive numbers
    progression Sum of ten consecutive numbers is 105. Determine these numbers (write first and last).
  • Three ints
    2016_hny The sum of three consecutive integers is 2016. What numbers are they?
  • Sequence 11
    sequence_geo_2 What is the nth term of this sequence 1,1/2,1/3,1/4,1/5 ?
  • Find the sum
    arithmet_seq_2 Find the sum of all natural numbers from 1 and 100, which are divisible by 2 or 5
  • AP members
    arithmet_seq What is the value of x2, x3, x4, x5…of the terms (of arithmetic progression) when x1 = 8 and x6 = 20?
  • Pool
    pool If water flows into the pool by two inlets, fill the whole for 19 hours. The first inlet filled pool 5 hour longer than the second. How long pool take to fill with two inlets separately?
  • AS sequence
    AP In an arithmetic sequence is given the difference d = -3 and a71 = 455. a) Determine the value of a62 b) Determine the sum of 71 members.
  • Self-counting machine
    nisa_Samopočet The self-counting machine works exactly like a calculator. The innkeeper wanted to add several three-digit natural numbers on his own. On the first attempt, he got the result in 2224. To check, he added these numbers again and he got 2198. Therefore, he a