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Finding the Fourth Proportional to 860.72, 1,290.40 and 427.64

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Solution

The fourth proportional to 860.72, 1,290.40 and 427.64 is: 641.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.72 : 1,290.40 = 427.64 : x
  2. Step 2: Convert to fraction form
    860.72/1,290.40 = 427.64/x
  3. Step 3: Cross multiply
    860.72x = 1,290.40 × 427.64
  4. Step 4: Simplify right side
    860.72x = 551,826.66
  5. Step 5: Solve for x
    x = 551,826.66/860.72
  6. Step 6: Final answer
    x = 641.12

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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.