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Finding the Fourth Proportional to 143.40, 215.49 and 78.45

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Solution

The fourth proportional to 143.40, 215.49 and 78.45 is: 117.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.40 : 215.49 = 78.45 : x
  2. Step 2: Convert to fraction form
    143.40/215.49 = 78.45/x
  3. Step 3: Cross multiply
    143.40x = 215.49 × 78.45
  4. Step 4: Simplify right side
    143.40x = 16,905.19
  5. Step 5: Solve for x
    x = 16,905.19/143.40
  6. Step 6: Final answer
    x = 117.89

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.