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Finding the Fourth Proportional to 115.38, 172.88 and 84.90

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Solution

The fourth proportional to 115.38, 172.88 and 84.90 is: 127.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.38 : 172.88 = 84.90 : x
  2. Step 2: Convert to fraction form
    115.38/172.88 = 84.90/x
  3. Step 3: Cross multiply
    115.38x = 172.88 × 84.90
  4. Step 4: Simplify right side
    115.38x = 14,677.51
  5. Step 5: Solve for x
    x = 14,677.51/115.38
  6. Step 6: Final answer
    x = 127.21

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.