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Finding the Fourth Proportional to 15,309, 21,128.04 and 9,720

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Solution

The fourth proportional to 15,309, 21,128.04 and 9,720 is: 13,414.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    15,309 : 21,128.04 = 9,720 : x
  2. Step 2: Convert to fraction form
    15,309/21,128.04 = 9,720/x
  3. Step 3: Cross multiply
    15,309x = 21,128.04 × 9,720
  4. Step 4: Simplify right side
    15,309x = 205,364,548.80
  5. Step 5: Solve for x
    x = 205,364,548.80/15,309
  6. Step 6: Final answer
    x = 13,414.63

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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.