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Finding the Fourth Proportional to 860.67, 1,290.10 and 421.31

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Solution

The fourth proportional to 860.67, 1,290.10 and 421.31 is: 631.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.67 : 1,290.10 = 421.31 : x
  2. Step 2: Convert to fraction form
    860.67/1,290.10 = 421.31/x
  3. Step 3: Cross multiply
    860.67x = 1,290.10 × 421.31
  4. Step 4: Simplify right side
    860.67x = 543,537.99
  5. Step 5: Solve for x
    x = 543,537.99/860.67
  6. Step 6: Final answer
    x = 631.53

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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.