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Finding the Fourth Proportional to 810.74, 1,215.84 and 421.22

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Solution

The fourth proportional to 810.74, 1,215.84 and 421.22 is: 631.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    810.74 : 1,215.84 = 421.22 : x
  2. Step 2: Convert to fraction form
    810.74/1,215.84 = 421.22/x
  3. Step 3: Cross multiply
    810.74x = 1,215.84 × 421.22
  4. Step 4: Simplify right side
    810.74x = 512,136.12
  5. Step 5: Solve for x
    x = 512,136.12/810.74
  6. Step 6: Final answer
    x = 631.69

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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.