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Finding the Fourth Proportional to 840.90, 1,160.70 and 491.88

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Solution

The fourth proportional to 840.90, 1,160.70 and 491.88 is: 678.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.90 : 1,160.70 = 491.88 : x
  2. Step 2: Convert to fraction form
    840.90/1,160.70 = 491.88/x
  3. Step 3: Cross multiply
    840.90x = 1,160.70 × 491.88
  4. Step 4: Simplify right side
    840.90x = 570,925.12
  5. Step 5: Solve for x
    x = 570,925.12/840.90
  6. Step 6: Final answer
    x = 678.95

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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.