Home / 81-111.78-47.80

Finding the Fourth Proportional to 81, 111.78 and 47.80

Calculator

Solution

The fourth proportional to 81, 111.78 and 47.80 is: 65.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    81 : 111.78 = 47.80 : x
  2. Step 2: Convert to fraction form
    81/111.78 = 47.80/x
  3. Step 3: Cross multiply
    81x = 111.78 × 47.80
  4. Step 4: Simplify right side
    81x = 5,343.08
  5. Step 5: Solve for x
    x = 5,343.08/81
  6. Step 6: Final answer
    x = 65.96

Related Problems

Find fourth proportional to 40.50, 55.89 and 23.90
Half scale
Find fourth proportional to 162, 223.56 and 95.60
Double scale
Find fourth proportional to 82, 113.16 and 48.80
Similar ratio
Find fourth proportional to 121.50, 167.67 and 71.70
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.