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Finding the Fourth Proportional to 100.65, 138.80 and 65.63

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Solution

The fourth proportional to 100.65, 138.80 and 65.63 is: 90.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.65 : 138.80 = 65.63 : x
  2. Step 2: Convert to fraction form
    100.65/138.80 = 65.63/x
  3. Step 3: Cross multiply
    100.65x = 138.80 × 65.63
  4. Step 4: Simplify right side
    100.65x = 9,109.44
  5. Step 5: Solve for x
    x = 9,109.44/100.65
  6. Step 6: Final answer
    x = 90.51

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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.