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Finding the Fourth Proportional to 115.30, 172.31 and 91

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Solution

The fourth proportional to 115.30, 172.31 and 91 is: 135.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.30 : 172.31 = 91 : x
  2. Step 2: Convert to fraction form
    115.30/172.31 = 91/x
  3. Step 3: Cross multiply
    115.30x = 172.31 × 91
  4. Step 4: Simplify right side
    115.30x = 15,680.21
  5. Step 5: Solve for x
    x = 15,680.21/115.30
  6. Step 6: Final answer
    x = 135.99

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.