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Finding the Fourth Proportional to 840.78, 1,160.28 and 491.46

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Solution

The fourth proportional to 840.78, 1,160.28 and 491.46 is: 678.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.78 : 1,160.28 = 491.46 : x
  2. Step 2: Convert to fraction form
    840.78/1,160.28 = 491.46/x
  3. Step 3: Cross multiply
    840.78x = 1,160.28 × 491.46
  4. Step 4: Simplify right side
    840.78x = 570,231.21
  5. Step 5: Solve for x
    x = 570,231.21/840.78
  6. Step 6: Final answer
    x = 678.22

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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.