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Finding the Fourth Proportional to 1,122.71, 1,686.49 and 917.78

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Solution

The fourth proportional to 1,122.71, 1,686.49 and 917.78 is: 1,378.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,122.71 : 1,686.49 = 917.78 : x
  2. Step 2: Convert to fraction form
    1,122.71/1,686.49 = 917.78/x
  3. Step 3: Cross multiply
    1,122.71x = 1,686.49 × 917.78
  4. Step 4: Simplify right side
    1,122.71x = 1,547,813.77
  5. Step 5: Solve for x
    x = 1,547,813.77/1,122.71
  6. Step 6: Final answer
    x = 1,378.65

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.