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Finding the Fourth Proportional to 312.65, 431.47 and 172.78

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Solution

The fourth proportional to 312.65, 431.47 and 172.78 is: 238.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.65 : 431.47 = 172.78 : x
  2. Step 2: Convert to fraction form
    312.65/431.47 = 172.78/x
  3. Step 3: Cross multiply
    312.65x = 431.47 × 172.78
  4. Step 4: Simplify right side
    312.65x = 74,549.39
  5. Step 5: Solve for x
    x = 74,549.39/312.65
  6. Step 6: Final answer
    x = 238.44

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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.