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Finding the Fourth Proportional to 1,388.80, 1,916.36 and 791.28

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Solution

The fourth proportional to 1,388.80, 1,916.36 and 791.28 is: 1,091.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,388.80 : 1,916.36 = 791.28 : x
  2. Step 2: Convert to fraction form
    1,388.80/1,916.36 = 791.28/x
  3. Step 3: Cross multiply
    1,388.80x = 1,916.36 × 791.28
  4. Step 4: Simplify right side
    1,388.80x = 1,516,377.34
  5. Step 5: Solve for x
    x = 1,516,377.34/1,388.80
  6. Step 6: Final answer
    x = 1,091.86

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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.