Home / 405.90-608.91-128.28

Finding the Fourth Proportional to 405.90, 608.91 and 128.28

Calculator

Solution

The fourth proportional to 405.90, 608.91 and 128.28 is: 192.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    405.90 : 608.91 = 128.28 : x
  2. Step 2: Convert to fraction form
    405.90/608.91 = 128.28/x
  3. Step 3: Cross multiply
    405.90x = 608.91 × 128.28
  4. Step 4: Simplify right side
    405.90x = 78,110.97
  5. Step 5: Solve for x
    x = 78,110.97/405.90
  6. Step 6: Final answer
    x = 192.44

Related Problems

Find fourth proportional to 202.95, 304.46 and 64.14
Half scale
Find fourth proportional to 811.80, 1,217.82 and 256.56
Double scale
Find fourth proportional to 406.90, 610.41 and 129.28
Similar ratio
Find fourth proportional to 608.85, 913.37 and 192.42
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.