Home / 398.78-550.27-221.70

Finding the Fourth Proportional to 398.78, 550.27 and 221.70

Calculator

Solution

The fourth proportional to 398.78, 550.27 and 221.70 is: 305.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    398.78 : 550.27 = 221.70 : x
  2. Step 2: Convert to fraction form
    398.78/550.27 = 221.70/x
  3. Step 3: Cross multiply
    398.78x = 550.27 × 221.70
  4. Step 4: Simplify right side
    398.78x = 121,994.86
  5. Step 5: Solve for x
    x = 121,994.86/398.78
  6. Step 6: Final answer
    x = 305.92

Related Problems

Find fourth proportional to 199.39, 275.14 and 110.85
Half scale
Find fourth proportional to 797.56, 1,100.54 and 443.40
Double scale
Find fourth proportional to 399.78, 551.65 and 222.70
Similar ratio
Find fourth proportional to 598.17, 825.41 and 332.55
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.