Home / 615.80-920.82-431.90

Finding the Fourth Proportional to 615.80, 920.82 and 431.90

Calculator

Solution

The fourth proportional to 615.80, 920.82 and 431.90 is: 645.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    615.80 : 920.82 = 431.90 : x
  2. Step 2: Convert to fraction form
    615.80/920.82 = 431.90/x
  3. Step 3: Cross multiply
    615.80x = 920.82 × 431.90
  4. Step 4: Simplify right side
    615.80x = 397,702.16
  5. Step 5: Solve for x
    x = 397,702.16/615.80
  6. Step 6: Final answer
    x = 645.83

Related Problems

Find fourth proportional to 307.90, 460.41 and 215.95
Half scale
Find fourth proportional to 1,231.60, 1,841.64 and 863.80
Double scale
Find fourth proportional to 616.80, 922.32 and 432.90
Similar ratio
Find fourth proportional to 923.70, 1,381.23 and 647.85
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.