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Finding the Fourth Proportional to 971.38, 1,340.72 and 639.84

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Solution

The fourth proportional to 971.38, 1,340.72 and 639.84 is: 883.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    971.38 : 1,340.72 = 639.84 : x
  2. Step 2: Convert to fraction form
    971.38/1,340.72 = 639.84/x
  3. Step 3: Cross multiply
    971.38x = 1,340.72 × 639.84
  4. Step 4: Simplify right side
    971.38x = 857,850.51
  5. Step 5: Solve for x
    x = 857,850.51/971.38
  6. Step 6: Final answer
    x = 883.12

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.