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Finding the Fourth Proportional to 811.50, 1,216.68 and 421.17

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Solution

The fourth proportional to 811.50, 1,216.68 and 421.17 is: 631.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.50 : 1,216.68 = 421.17 : x
  2. Step 2: Convert to fraction form
    811.50/1,216.68 = 421.17/x
  3. Step 3: Cross multiply
    811.50x = 1,216.68 × 421.17
  4. Step 4: Simplify right side
    811.50x = 512,429.12
  5. Step 5: Solve for x
    x = 512,429.12/811.50
  6. Step 6: Final answer
    x = 631.46

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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.