Home / 218.87-328.28-81.90

Finding the Fourth Proportional to 218.87, 328.28 and 81.90

Calculator

Solution

The fourth proportional to 218.87, 328.28 and 81.90 is: 122.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    218.87 : 328.28 = 81.90 : x
  2. Step 2: Convert to fraction form
    218.87/328.28 = 81.90/x
  3. Step 3: Cross multiply
    218.87x = 328.28 × 81.90
  4. Step 4: Simplify right side
    218.87x = 26,885.72
  5. Step 5: Solve for x
    x = 26,885.72/218.87
  6. Step 6: Final answer
    x = 122.84

Related Problems

Find fourth proportional to 109.44, 164.14 and 40.95
Half scale
Find fourth proportional to 437.75, 656.55 and 163.80
Double scale
Find fourth proportional to 219.87, 329.77 and 82.90
Similar ratio
Find fourth proportional to 328.31, 492.41 and 122.85
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.