Home / 280.80-421.38-209.10

Finding the Fourth Proportional to 280.80, 421.38 and 209.10

Calculator

Solution

The fourth proportional to 280.80, 421.38 and 209.10 is: 313.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.80 : 421.38 = 209.10 : x
  2. Step 2: Convert to fraction form
    280.80/421.38 = 209.10/x
  3. Step 3: Cross multiply
    280.80x = 421.38 × 209.10
  4. Step 4: Simplify right side
    280.80x = 88,110.56
  5. Step 5: Solve for x
    x = 88,110.56/280.80
  6. Step 6: Final answer
    x = 313.78

Related Problems

Find fourth proportional to 140.40, 210.69 and 104.55
Half scale
Find fourth proportional to 561.60, 842.76 and 418.20
Double scale
Find fourth proportional to 281.80, 422.88 and 210.10
Similar ratio
Find fourth proportional to 421.20, 632.07 and 313.65
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.