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Finding the Fourth Proportional to 309.76, 428.40 and 275.36

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Solution

The fourth proportional to 309.76, 428.40 and 275.36 is: 380.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    309.76 : 428.40 = 275.36 : x
  2. Step 2: Convert to fraction form
    309.76/428.40 = 275.36/x
  3. Step 3: Cross multiply
    309.76x = 428.40 × 275.36
  4. Step 4: Simplify right side
    309.76x = 117,964.22
  5. Step 5: Solve for x
    x = 117,964.22/309.76
  6. Step 6: Final answer
    x = 380.82

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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.