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Finding the Fourth Proportional to 860.54, 1,290.86 and 312.78

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Solution

The fourth proportional to 860.54, 1,290.86 and 312.78 is: 469.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.54 : 1,290.86 = 312.78 : x
  2. Step 2: Convert to fraction form
    860.54/1,290.86 = 312.78/x
  3. Step 3: Cross multiply
    860.54x = 1,290.86 × 312.78
  4. Step 4: Simplify right side
    860.54x = 403,755.19
  5. Step 5: Solve for x
    x = 403,755.19/860.54
  6. Step 6: Final answer
    x = 469.19

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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.