Home / 101.28-139.60-77.90

Finding the Fourth Proportional to 101.28, 139.60 and 77.90

Calculator

Solution

The fourth proportional to 101.28, 139.60 and 77.90 is: 107.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    101.28 : 139.60 = 77.90 : x
  2. Step 2: Convert to fraction form
    101.28/139.60 = 77.90/x
  3. Step 3: Cross multiply
    101.28x = 139.60 × 77.90
  4. Step 4: Simplify right side
    101.28x = 10,874.84
  5. Step 5: Solve for x
    x = 10,874.84/101.28
  6. Step 6: Final answer
    x = 107.37

Related Problems

Find fourth proportional to 50.64, 69.80 and 38.95
Half scale
Find fourth proportional to 202.56, 279.20 and 155.80
Double scale
Find fourth proportional to 102.28, 140.98 and 78.90
Similar ratio
Find fourth proportional to 151.92, 209.40 and 116.85
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.