Home / 76.80-115.28-59.86

Finding the Fourth Proportional to 76.80, 115.28 and 59.86

Calculator

Solution

The fourth proportional to 76.80, 115.28 and 59.86 is: 89.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.80 : 115.28 = 59.86 : x
  2. Step 2: Convert to fraction form
    76.80/115.28 = 59.86/x
  3. Step 3: Cross multiply
    76.80x = 115.28 × 59.86
  4. Step 4: Simplify right side
    76.80x = 6,900.66
  5. Step 5: Solve for x
    x = 6,900.66/76.80
  6. Step 6: Final answer
    x = 89.85

Related Problems

Find fourth proportional to 38.40, 57.64 and 29.93
Half scale
Find fourth proportional to 153.60, 230.56 and 119.72
Double scale
Find fourth proportional to 77.80, 116.78 and 60.86
Similar ratio
Find fourth proportional to 115.20, 172.92 and 89.79
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.