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Finding the Fourth Proportional to 1,428.71, 1,971.25 and 839.13

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Solution

The fourth proportional to 1,428.71, 1,971.25 and 839.13 is: 1,157.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,428.71 : 1,971.25 = 839.13 : x
  2. Step 2: Convert to fraction form
    1,428.71/1,971.25 = 839.13/x
  3. Step 3: Cross multiply
    1,428.71x = 1,971.25 × 839.13
  4. Step 4: Simplify right side
    1,428.71x = 1,654,125.52
  5. Step 5: Solve for x
    x = 1,654,125.52/1,428.71
  6. Step 6: Final answer
    x = 1,157.78

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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.