Math Problem Statement

There are seven arithmetic means between betweeen 3 and 35. Find the sum of all the terms

Solution

To find the sum of all the terms, including the seven arithmetic means between 3 and 35, we first need to determine the terms in the arithmetic sequence.

Step 1: Determine the number of terms in the sequence

There are seven arithmetic means between 3 and 35. So, including 3 and 35, the total number of terms nn in the sequence is: n=7+2=9n = 7 + 2 = 9

Step 2: Determine the common difference dd

The general formula for the nn-th term of an arithmetic sequence is: an=a1+(n1)da_n = a_1 + (n-1)d Here:

  • a1=3a_1 = 3 (the first term)
  • a9=35a_9 = 35 (the ninth term)

Substitute the known values into the formula for the ninth term: 35=3+(91)d35 = 3 + (9-1)d 35=3+8d35 = 3 + 8d 8d=353=328d = 35 - 3 = 32 d=328=4d = \frac{32}{8} = 4 So, the common difference dd is 4.

Step 3: Determine all the terms

Now that we have the common difference d=4d = 4, we can find all the terms of the sequence:

  • First term a1=3a_1 = 3
  • Second term a2=3+4=7a_2 = 3 + 4 = 7
  • Third term a3=7+4=11a_3 = 7 + 4 = 11
  • Fourth term a4=11+4=15a_4 = 11 + 4 = 15
  • Fifth term a5=15+4=19a_5 = 15 + 4 = 19
  • Sixth term a6=19+4=23a_6 = 19 + 4 = 23
  • Seventh term a7=23+4=27a_7 = 23 + 4 = 27
  • Eighth term a8=27+4=31a_8 = 27 + 4 = 31
  • Ninth term a9=35a_9 = 35

So, the sequence is: 3,7,11,15,19,23,27,31,353, 7, 11, 15, 19, 23, 27, 31, 35

Step 4: Calculate the sum of the sequence

The sum SnS_n of an arithmetic sequence can be calculated using the formula: Sn=n2×(a1+an)S_n = \frac{n}{2} \times (a_1 + a_n) Substituting the known values: S9=92×(3+35)=92×38=9×382=3422=171S_9 = \frac{9}{2} \times (3 + 35) = \frac{9}{2} \times 38 = \frac{9 \times 38}{2} = \frac{342}{2} = 171

Final Answer

The sum of all the terms in the sequence is 171.

Would you like further details or have any questions about this? Here are five related questions you might find interesting:

  1. How do you find the number of terms in an arithmetic sequence when only the first and last terms are given?
  2. How can you determine the common difference if you only know the first term and the total sum of the sequence?
  3. What is the formula for the nth term of an arithmetic sequence and how can it be used in different scenarios?
  4. How would you find the sum of a sequence if the number of terms was unknown but the common difference was given?
  5. How does the sum of an arithmetic series change if the common difference is negative?

Tip: When dealing with arithmetic sequences, always check if you have all the required values (first term, last term, number of terms, or common difference) to use the appropriate formulas efficiently.

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Math Problem Analysis

Mathematical Concepts

Arithmetic Sequences
Sum of Arithmetic Sequences

Formulas

Arithmetic sequence nth term formula
Sum of arithmetic sequence formula

Theorems

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Suitable Grade Level

Grades 7-9