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Finding the Fourth Proportional to 103.65, 155.49 and 78

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Solution

The fourth proportional to 103.65, 155.49 and 78 is: 117.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.65 : 155.49 = 78 : x
  2. Step 2: Convert to fraction form
    103.65/155.49 = 78/x
  3. Step 3: Cross multiply
    103.65x = 155.49 × 78
  4. Step 4: Simplify right side
    103.65x = 12,128.22
  5. Step 5: Solve for x
    x = 12,128.22/103.65
  6. Step 6: Final answer
    x = 117.01

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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.