Home / 84.87-126.54-81.90

Finding the Fourth Proportional to 84.87, 126.54 and 81.90

Calculator

Solution

The fourth proportional to 84.87, 126.54 and 81.90 is: 122.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.87 : 126.54 = 81.90 : x
  2. Step 2: Convert to fraction form
    84.87/126.54 = 81.90/x
  3. Step 3: Cross multiply
    84.87x = 126.54 × 81.90
  4. Step 4: Simplify right side
    84.87x = 10,363.63
  5. Step 5: Solve for x
    x = 10,363.63/84.87
  6. Step 6: Final answer
    x = 122.11

Related Problems

Find fourth proportional to 42.44, 63.27 and 40.95
Half scale
Find fourth proportional to 169.74, 253.08 and 163.80
Double scale
Find fourth proportional to 85.87, 128.03 and 82.90
Similar ratio
Find fourth proportional to 127.31, 189.81 and 122.85
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.