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Finding the Fourth Proportional to 103.80, 143.40 and 90

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Solution

The fourth proportional to 103.80, 143.40 and 90 is: 124.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.80 : 143.40 = 90 : x
  2. Step 2: Convert to fraction form
    103.80/143.40 = 90/x
  3. Step 3: Cross multiply
    103.80x = 143.40 × 90
  4. Step 4: Simplify right side
    103.80x = 12,906
  5. Step 5: Solve for x
    x = 12,906/103.80
  6. Step 6: Final answer
    x = 124.34

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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.