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Finding the Fourth Proportional to 21,271, 31,921.11 and 7,420

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Solution

The fourth proportional to 21,271, 31,921.11 and 7,420 is: 11,135.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    21,271 : 31,921.11 = 7,420 : x
  2. Step 2: Convert to fraction form
    21,271/31,921.11 = 7,420/x
  3. Step 3: Cross multiply
    21,271x = 31,921.11 × 7,420
  4. Step 4: Simplify right side
    21,271x = 236,854,636.20
  5. Step 5: Solve for x
    x = 236,854,636.20/21,271
  6. Step 6: Final answer
    x = 11,135.10

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.