Home / 69.78-104.65-42.70

Finding the Fourth Proportional to 69.78, 104.65 and 42.70

Calculator

Solution

The fourth proportional to 69.78, 104.65 and 42.70 is: 64.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    69.78 : 104.65 = 42.70 : x
  2. Step 2: Convert to fraction form
    69.78/104.65 = 42.70/x
  3. Step 3: Cross multiply
    69.78x = 104.65 × 42.70
  4. Step 4: Simplify right side
    69.78x = 4,468.56
  5. Step 5: Solve for x
    x = 4,468.56/69.78
  6. Step 6: Final answer
    x = 64.04

Related Problems

Find fourth proportional to 34.89, 52.33 and 21.35
Half scale
Find fourth proportional to 139.56, 209.30 and 85.40
Double scale
Find fourth proportional to 70.78, 106.15 and 43.70
Similar ratio
Find fourth proportional to 104.67, 156.98 and 64.05
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.