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Finding the Fourth Proportional to 661.78, 991.86 and 479.80

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Solution

The fourth proportional to 661.78, 991.86 and 479.80 is: 719.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.78 : 991.86 = 479.80 : x
  2. Step 2: Convert to fraction form
    661.78/991.86 = 479.80/x
  3. Step 3: Cross multiply
    661.78x = 991.86 × 479.80
  4. Step 4: Simplify right side
    661.78x = 475,894.43
  5. Step 5: Solve for x
    x = 475,894.43/661.78
  6. Step 6: Final answer
    x = 719.11

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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.