Home / 77.60-115.78-66.72

Finding the Fourth Proportional to 77.60, 115.78 and 66.72

Calculator

Solution

The fourth proportional to 77.60, 115.78 and 66.72 is: 99.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.60 : 115.78 = 66.72 : x
  2. Step 2: Convert to fraction form
    77.60/115.78 = 66.72/x
  3. Step 3: Cross multiply
    77.60x = 115.78 × 66.72
  4. Step 4: Simplify right side
    77.60x = 7,724.84
  5. Step 5: Solve for x
    x = 7,724.84/77.60
  6. Step 6: Final answer
    x = 99.55

Related Problems

Find fourth proportional to 38.80, 57.89 and 33.36
Half scale
Find fourth proportional to 155.20, 231.56 and 133.44
Double scale
Find fourth proportional to 78.60, 117.27 and 67.72
Similar ratio
Find fourth proportional to 116.40, 173.67 and 100.08
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.