Home / 642.58-963.92-209.78

Finding the Fourth Proportional to 642.58, 963.92 and 209.78

Calculator

Solution

The fourth proportional to 642.58, 963.92 and 209.78 is: 314.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.58 : 963.92 = 209.78 : x
  2. Step 2: Convert to fraction form
    642.58/963.92 = 209.78/x
  3. Step 3: Cross multiply
    642.58x = 963.92 × 209.78
  4. Step 4: Simplify right side
    642.58x = 202,211.14
  5. Step 5: Solve for x
    x = 202,211.14/642.58
  6. Step 6: Final answer
    x = 314.69

Related Problems

Find fourth proportional to 321.29, 481.96 and 104.89
Half scale
Find fourth proportional to 1,285.16, 1,927.84 and 419.56
Double scale
Find fourth proportional to 643.58, 965.42 and 210.78
Similar ratio
Find fourth proportional to 963.87, 1,445.88 and 314.67
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.