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Finding the Fourth Proportional to 1,085.78, 1,498.10 and 643.44

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Solution

The fourth proportional to 1,085.78, 1,498.10 and 643.44 is: 887.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,085.78 : 1,498.10 = 643.44 : x
  2. Step 2: Convert to fraction form
    1,085.78/1,498.10 = 643.44/x
  3. Step 3: Cross multiply
    1,085.78x = 1,498.10 × 643.44
  4. Step 4: Simplify right side
    1,085.78x = 963,937.46
  5. Step 5: Solve for x
    x = 963,937.46/1,085.78
  6. Step 6: Final answer
    x = 887.78

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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.