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Finding the Fourth Proportional to 1,118.78, 1,678.40 and 388.41

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Solution

The fourth proportional to 1,118.78, 1,678.40 and 388.41 is: 582.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,118.78 : 1,678.40 = 388.41 : x
  2. Step 2: Convert to fraction form
    1,118.78/1,678.40 = 388.41/x
  3. Step 3: Cross multiply
    1,118.78x = 1,678.40 × 388.41
  4. Step 4: Simplify right side
    1,118.78x = 651,897.01
  5. Step 5: Solve for x
    x = 651,897.01/1,118.78
  6. Step 6: Final answer
    x = 582.69

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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.