Home / 97.20-128.40-97.20

Finding the Fourth Proportional to 97.20, 128.40 and 97.20

Calculator

Solution

The fourth proportional to 97.20, 128.40 and 97.20 is: 128.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    97.20 : 128.40 = 97.20 : x
  2. Step 2: Convert to fraction form
    97.20/128.40 = 97.20/x
  3. Step 3: Cross multiply
    97.20x = 128.40 × 97.20
  4. Step 4: Simplify right side
    97.20x = 12,480.48
  5. Step 5: Solve for x
    x = 12,480.48/97.20
  6. Step 6: Final answer
    x = 128.40

Related Problems

Find fourth proportional to 48.60, 64.20 and 48.60
Half scale
Find fourth proportional to 194.40, 256.80 and 194.40
Double scale
Find fourth proportional to 98.20, 129.72 and 98.20
Similar ratio
Find fourth proportional to 145.80, 192.60 and 145.80
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.32) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.