Home / 129.30-178.43-85.72

Finding the Fourth Proportional to 129.30, 178.43 and 85.72

Calculator

Solution

The fourth proportional to 129.30, 178.43 and 85.72 is: 118.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.30 : 178.43 = 85.72 : x
  2. Step 2: Convert to fraction form
    129.30/178.43 = 85.72/x
  3. Step 3: Cross multiply
    129.30x = 178.43 × 85.72
  4. Step 4: Simplify right side
    129.30x = 15,294.02
  5. Step 5: Solve for x
    x = 15,294.02/129.30
  6. Step 6: Final answer
    x = 118.29

Related Problems

Find fourth proportional to 64.65, 89.21 and 42.86
Half scale
Find fourth proportional to 258.60, 356.86 and 171.43
Double scale
Find fourth proportional to 130.30, 179.81 and 86.72
Similar ratio
Find fourth proportional to 193.95, 267.64 and 128.57
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.