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Finding the Fourth Proportional to 115.40, 172.74 and 79.31

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Solution

The fourth proportional to 115.40, 172.74 and 79.31 is: 118.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.40 : 172.74 = 79.31 : x
  2. Step 2: Convert to fraction form
    115.40/172.74 = 79.31/x
  3. Step 3: Cross multiply
    115.40x = 172.74 × 79.31
  4. Step 4: Simplify right side
    115.40x = 13,700.01
  5. Step 5: Solve for x
    x = 13,700.01/115.40
  6. Step 6: Final answer
    x = 118.72

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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.