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Finding the Fourth Proportional to 312.79, 431.62 and 172.91

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Solution

The fourth proportional to 312.79, 431.62 and 172.91 is: 238.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.79 : 431.62 = 172.91 : x
  2. Step 2: Convert to fraction form
    312.79/431.62 = 172.91/x
  3. Step 3: Cross multiply
    312.79x = 431.62 × 172.91
  4. Step 4: Simplify right side
    312.79x = 74,630.55
  5. Step 5: Solve for x
    x = 74,630.55/312.79
  6. Step 6: Final answer
    x = 238.60

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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.