Home / 124.80-187.20-86.20

Finding the Fourth Proportional to 124.80, 187.20 and 86.20

Calculator

Solution

The fourth proportional to 124.80, 187.20 and 86.20 is: 129.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    124.80 : 187.20 = 86.20 : x
  2. Step 2: Convert to fraction form
    124.80/187.20 = 86.20/x
  3. Step 3: Cross multiply
    124.80x = 187.20 × 86.20
  4. Step 4: Simplify right side
    124.80x = 16,136.64
  5. Step 5: Solve for x
    x = 16,136.64/124.80
  6. Step 6: Final answer
    x = 129.30

Related Problems

Find fourth proportional to 62.40, 93.60 and 43.10
Half scale
Find fourth proportional to 249.60, 374.40 and 172.40
Double scale
Find fourth proportional to 125.80, 188.70 and 87.20
Similar ratio
Find fourth proportional to 187.20, 280.80 and 129.30
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.