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Finding the Fourth Proportional to 783.90, 1,176.60 and 639.30

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Solution

The fourth proportional to 783.90, 1,176.60 and 639.30 is: 959.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    783.90 : 1,176.60 = 639.30 : x
  2. Step 2: Convert to fraction form
    783.90/1,176.60 = 639.30/x
  3. Step 3: Cross multiply
    783.90x = 1,176.60 × 639.30
  4. Step 4: Simplify right side
    783.90x = 752,200.38
  5. Step 5: Solve for x
    x = 752,200.38/783.90
  6. Step 6: Final answer
    x = 959.56

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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.