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Finding the Fourth Proportional to 165.49, 247.90 and 78.70

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Solution

The fourth proportional to 165.49, 247.90 and 78.70 is: 117.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    165.49 : 247.90 = 78.70 : x
  2. Step 2: Convert to fraction form
    165.49/247.90 = 78.70/x
  3. Step 3: Cross multiply
    165.49x = 247.90 × 78.70
  4. Step 4: Simplify right side
    165.49x = 19,509.34
  5. Step 5: Solve for x
    x = 19,509.34/165.49
  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.