CSCAPrep
Reviewed CSCA Mathematics question · Easy

In an arithmetic sequence, the 4th term is 15 and the 8th term is 27. What is the 12th term?

  1. 39
  2. 41
  3. 43
  4. 45
Show the answer and explanation

Correct answer

A. 39

Principle or equation

In an arithmetic sequence, the nth term is a_n = a_1 + (n-1)d. The difference between terms is constant.

Why this answer is correct

Let a_4 = a_1 + 3d = 15 and a_8 = a_1 + 7d = 27. Subtract: 4d = 12, so d = 3. Then a_1 = 15 - 3*3 = 6. Then a_12 = 6 + 11*3 = 39.

Example

If a_3=10 and a_7=26, then d=(26-10)/4=4, a_1=2, a_10=2+9*4=38.

This published item includes a stored explanation and passed the platform’s publication workflow. It is independent preparation material, not a claim of an official or recalled examination question.

Related practice questions

Standard · FunctionsIf f(x) = 2x − 5, what is f⁻¹(x)?Standard · FunctionsIf f(x) = 2x − 5, what is f⁻¹(x)?Standard · FunctionsIn a geometric sequence, the first term is 2 and the common ratio is 3. What is the sum of the first…Standard · FunctionsWhat is the domain of the function f(x) = sqrt(2x - 6) / (x - 5)?Standard · FunctionsSolve for x: log₃(x) + log₃(x - 2) = 1.