Home / 142.71-214.08-81.78

Finding the Fourth Proportional to 142.71, 214.08 and 81.78

Calculator

Solution

The fourth proportional to 142.71, 214.08 and 81.78 is: 122.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.71 : 214.08 = 81.78 : x
  2. Step 2: Convert to fraction form
    142.71/214.08 = 81.78/x
  3. Step 3: Cross multiply
    142.71x = 214.08 × 81.78
  4. Step 4: Simplify right side
    142.71x = 17,507.46
  5. Step 5: Solve for x
    x = 17,507.46/142.71
  6. Step 6: Final answer
    x = 122.68

Related Problems

Find fourth proportional to 71.36, 107.04 and 40.89
Half scale
Find fourth proportional to 285.42, 428.16 and 163.56
Double scale
Find fourth proportional to 143.71, 215.58 and 82.78
Similar ratio
Find fourth proportional to 214.07, 321.12 and 122.67
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.