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Finding the Fourth Proportional to 105.45, 145.42 and 90.87

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Solution

The fourth proportional to 105.45, 145.42 and 90.87 is: 125.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    105.45 : 145.42 = 90.87 : x
  2. Step 2: Convert to fraction form
    105.45/145.42 = 90.87/x
  3. Step 3: Cross multiply
    105.45x = 145.42 × 90.87
  4. Step 4: Simplify right side
    105.45x = 13,214.32
  5. Step 5: Solve for x
    x = 13,214.32/105.45
  6. Step 6: Final answer
    x = 125.31

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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.