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Finding the Fourth Proportional to 1,392.71, 1,918.68 and 972.31

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Solution

The fourth proportional to 1,392.71, 1,918.68 and 972.31 is: 1,339.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,392.71 : 1,918.68 = 972.31 : x
  2. Step 2: Convert to fraction form
    1,392.71/1,918.68 = 972.31/x
  3. Step 3: Cross multiply
    1,392.71x = 1,918.68 × 972.31
  4. Step 4: Simplify right side
    1,392.71x = 1,865,551.75
  5. Step 5: Solve for x
    x = 1,865,551.75/1,392.71
  6. Step 6: Final answer
    x = 1,339.51

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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.