If the 2nd term of a GP is 8 and the 4th term is 32, what is the common ratio?

Practice Questions

Q1
If the 2nd term of a GP is 8 and the 4th term is 32, what is the common ratio?
  1. 2
  2. 4
  3. 1/2
  4. 1/4

Questions & Step-by-Step Solutions

If the 2nd term of a GP is 8 and the 4th term is 32, what is the common ratio?
  • Step 1: Identify the first term of the geometric progression (GP) as 'a' and the common ratio as 'r'.
  • Step 2: Write the formula for the 2nd term of the GP, which is 'ar'. We know from the question that this equals 8, so we have the equation: ar = 8.
  • Step 3: Write the formula for the 4th term of the GP, which is 'ar^3'. We know from the question that this equals 32, so we have the equation: ar^3 = 32.
  • Step 4: Now we have two equations: ar = 8 and ar^3 = 32.
  • Step 5: To find the common ratio 'r', divide the second equation (ar^3 = 32) by the first equation (ar = 8). This gives us: (ar^3) / (ar) = 32 / 8.
  • Step 6: Simplifying the left side, we get r^2 = 4.
  • Step 7: To find 'r', take the square root of both sides. This gives us r = 2.
  • Geometric Progression (GP) – Understanding the properties of geometric sequences, including how to express terms in relation to the first term and common ratio.
  • Algebraic Manipulation – Skills in manipulating equations to isolate variables and solve for unknowns.
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