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Finding the Fourth Proportional to 1,345.20, 1,851.28 and 1,221

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Solution

The fourth proportional to 1,345.20, 1,851.28 and 1,221 is: 1,680.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,345.20 : 1,851.28 = 1,221 : x
  2. Step 2: Convert to fraction form
    1,345.20/1,851.28 = 1,221/x
  3. Step 3: Cross multiply
    1,345.20x = 1,851.28 × 1,221
  4. Step 4: Simplify right side
    1,345.20x = 2,260,412.88
  5. Step 5: Solve for x
    x = 2,260,412.88/1,345.20
  6. Step 6: Final answer
    x = 1,680.35

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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.