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Finding the Fourth Proportional to 1,389.66, 1,917.12 and 916.98

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Solution

The fourth proportional to 1,389.66, 1,917.12 and 916.98 is: 1,265.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.66 : 1,917.12 = 916.98 : x
  2. Step 2: Convert to fraction form
    1,389.66/1,917.12 = 916.98/x
  3. Step 3: Cross multiply
    1,389.66x = 1,917.12 × 916.98
  4. Step 4: Simplify right side
    1,389.66x = 1,757,960.70
  5. Step 5: Solve for x
    x = 1,757,960.70/1,389.66
  6. Step 6: Final answer
    x = 1,265.03

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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.