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Finding the Fourth Proportional to 810.58, 1,216.12 and 420.86

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Solution

The fourth proportional to 810.58, 1,216.12 and 420.86 is: 631.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    810.58 : 1,216.12 = 420.86 : x
  2. Step 2: Convert to fraction form
    810.58/1,216.12 = 420.86/x
  3. Step 3: Cross multiply
    810.58x = 1,216.12 × 420.86
  4. Step 4: Simplify right side
    810.58x = 511,816.26
  5. Step 5: Solve for x
    x = 511,816.26/810.58
  6. Step 6: Final answer
    x = 631.42

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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.