Home / 385.39-578.07-128.89

Finding the Fourth Proportional to 385.39, 578.07 and 128.89

Calculator

Solution

The fourth proportional to 385.39, 578.07 and 128.89 is: 193.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    385.39 : 578.07 = 128.89 : x
  2. Step 2: Convert to fraction form
    385.39/578.07 = 128.89/x
  3. Step 3: Cross multiply
    385.39x = 578.07 × 128.89
  4. Step 4: Simplify right side
    385.39x = 74,507.44
  5. Step 5: Solve for x
    x = 74,507.44/385.39
  6. Step 6: Final answer
    x = 193.33

Related Problems

Find fourth proportional to 192.70, 289.04 and 64.45
Half scale
Find fourth proportional to 770.78, 1,156.14 and 257.78
Double scale
Find fourth proportional to 386.39, 579.57 and 129.89
Similar ratio
Find fourth proportional to 578.09, 867.11 and 193.34
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.