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Finding the Fourth Proportional to 1,391.71, 1,917.30 and 971.31

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Solution

The fourth proportional to 1,391.71, 1,917.30 and 971.31 is: 1,338.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391.71 : 1,917.30 = 971.31 : x
  2. Step 2: Convert to fraction form
    1,391.71/1,917.30 = 971.31/x
  3. Step 3: Cross multiply
    1,391.71x = 1,917.30 × 971.31
  4. Step 4: Simplify right side
    1,391.71x = 1,862,292.66
  5. Step 5: Solve for x
    x = 1,862,292.66/1,391.71
  6. Step 6: Final answer
    x = 1,338.13

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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.