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Finding the Fourth Proportional to 72.65, 108.40 and 71.21

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Solution

The fourth proportional to 72.65, 108.40 and 71.21 is: 106.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.65 : 108.40 = 71.21 : x
  2. Step 2: Convert to fraction form
    72.65/108.40 = 71.21/x
  3. Step 3: Cross multiply
    72.65x = 108.40 × 71.21
  4. Step 4: Simplify right side
    72.65x = 7,719.16
  5. Step 5: Solve for x
    x = 7,719.16/72.65
  6. Step 6: Final answer
    x = 106.25

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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.