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Finding the Fourth Proportional to 810.40, 1,216.65 and 421.21

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Solution

The fourth proportional to 810.40, 1,216.65 and 421.21 is: 632.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    810.40 : 1,216.65 = 421.21 : x
  2. Step 2: Convert to fraction form
    810.40/1,216.65 = 421.21/x
  3. Step 3: Cross multiply
    810.40x = 1,216.65 × 421.21
  4. Step 4: Simplify right side
    810.40x = 512,465.15
  5. Step 5: Solve for x
    x = 512,465.15/810.40
  6. Step 6: Final answer
    x = 632.36

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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.