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Finding the Fourth Proportional to 978.78, 1,474.80 and 809.22

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Solution

The fourth proportional to 978.78, 1,474.80 and 809.22 is: 1,219.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.78 : 1,474.80 = 809.22 : x
  2. Step 2: Convert to fraction form
    978.78/1,474.80 = 809.22/x
  3. Step 3: Cross multiply
    978.78x = 1,474.80 × 809.22
  4. Step 4: Simplify right side
    978.78x = 1,193,437.66
  5. Step 5: Solve for x
    x = 1,193,437.66/978.78
  6. Step 6: Final answer
    x = 1,219.31

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.