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Finding the Fourth Proportional to 1,390.29, 1,916.91 and 865.41

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Solution

The fourth proportional to 1,390.29, 1,916.91 and 865.41 is: 1,193.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.29 : 1,916.91 = 865.41 : x
  2. Step 2: Convert to fraction form
    1,390.29/1,916.91 = 865.41/x
  3. Step 3: Cross multiply
    1,390.29x = 1,916.91 × 865.41
  4. Step 4: Simplify right side
    1,390.29x = 1,658,913.08
  5. Step 5: Solve for x
    x = 1,658,913.08/1,390.29
  6. Step 6: Final answer
    x = 1,193.21

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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.