Home / 120.78-181.08-86.58

Finding the Fourth Proportional to 120.78, 181.08 and 86.58

Calculator

Solution

The fourth proportional to 120.78, 181.08 and 86.58 is: 129.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.78 : 181.08 = 86.58 : x
  2. Step 2: Convert to fraction form
    120.78/181.08 = 86.58/x
  3. Step 3: Cross multiply
    120.78x = 181.08 × 86.58
  4. Step 4: Simplify right side
    120.78x = 15,677.91
  5. Step 5: Solve for x
    x = 15,677.91/120.78
  6. Step 6: Final answer
    x = 129.81

Related Problems

Find fourth proportional to 60.39, 90.54 and 43.29
Half scale
Find fourth proportional to 241.56, 362.16 and 173.16
Double scale
Find fourth proportional to 121.78, 182.58 and 87.58
Similar ratio
Find fourth proportional to 181.17, 271.62 and 129.87
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.