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Finding the Fourth Proportional to 172.79, 238.29 and 128.45

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Solution

The fourth proportional to 172.79, 238.29 and 128.45 is: 177.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.79 : 238.29 = 128.45 : x
  2. Step 2: Convert to fraction form
    172.79/238.29 = 128.45/x
  3. Step 3: Cross multiply
    172.79x = 238.29 × 128.45
  4. Step 4: Simplify right side
    172.79x = 30,608.35
  5. Step 5: Solve for x
    x = 30,608.35/172.79
  6. Step 6: Final answer
    x = 177.14

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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.