Home / 412.80-618.78-138.69

Finding the Fourth Proportional to 412.80, 618.78 and 138.69

Calculator

Solution

The fourth proportional to 412.80, 618.78 and 138.69 is: 207.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    412.80 : 618.78 = 138.69 : x
  2. Step 2: Convert to fraction form
    412.80/618.78 = 138.69/x
  3. Step 3: Cross multiply
    412.80x = 618.78 × 138.69
  4. Step 4: Simplify right side
    412.80x = 85,818.60
  5. Step 5: Solve for x
    x = 85,818.60/412.80
  6. Step 6: Final answer
    x = 207.89

Related Problems

Find fourth proportional to 206.40, 309.39 and 69.35
Half scale
Find fourth proportional to 825.60, 1,237.56 and 277.38
Double scale
Find fourth proportional to 413.80, 620.28 and 139.69
Similar ratio
Find fourth proportional to 619.20, 928.17 and 208.04
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.