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Finding the Fourth Proportional to 1,387.17, 1,913.67 and 855.81

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Solution

The fourth proportional to 1,387.17, 1,913.67 and 855.81 is: 1,180.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.17 : 1,913.67 = 855.81 : x
  2. Step 2: Convert to fraction form
    1,387.17/1,913.67 = 855.81/x
  3. Step 3: Cross multiply
    1,387.17x = 1,913.67 × 855.81
  4. Step 4: Simplify right side
    1,387.17x = 1,637,737.92
  5. Step 5: Solve for x
    x = 1,637,737.92/1,387.17
  6. Step 6: Final answer
    x = 1,180.63

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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.