Home / 51.20-76.80-39.18

Finding the Fourth Proportional to 51.20, 76.80 and 39.18

Calculator

Solution

The fourth proportional to 51.20, 76.80 and 39.18 is: 58.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    51.20 : 76.80 = 39.18 : x
  2. Step 2: Convert to fraction form
    51.20/76.80 = 39.18/x
  3. Step 3: Cross multiply
    51.20x = 76.80 × 39.18
  4. Step 4: Simplify right side
    51.20x = 3,009.02
  5. Step 5: Solve for x
    x = 3,009.02/51.20
  6. Step 6: Final answer
    x = 58.78

Related Problems

Find fourth proportional to 25.60, 38.40 and 19.59
Half scale
Find fourth proportional to 102.39, 153.60 and 78.36
Double scale
Find fourth proportional to 52.20, 78.30 and 40.18
Similar ratio
Find fourth proportional to 76.79, 115.20 and 58.77
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.