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Finding the Fourth Proportional to 100.42, 138.54 and 65.48

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Solution

The fourth proportional to 100.42, 138.54 and 65.48 is: 90.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.42 : 138.54 = 65.48 : x
  2. Step 2: Convert to fraction form
    100.42/138.54 = 65.48/x
  3. Step 3: Cross multiply
    100.42x = 138.54 × 65.48
  4. Step 4: Simplify right side
    100.42x = 9,071.60
  5. Step 5: Solve for x
    x = 9,071.60/100.42
  6. Step 6: Final answer
    x = 90.34

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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.