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Finding the Fourth Proportional to 10.85, 15.00 and 7.78

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Solution

The fourth proportional to 10.85, 15.00 and 7.78 is: 10.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    10.85 : 15.00 = 7.78 : x
  2. Step 2: Convert to fraction form
    10.85/15.00 = 7.78/x
  3. Step 3: Cross multiply
    10.85x = 15.00 × 7.78
  4. Step 4: Simplify right side
    10.85x = 116.65
  5. Step 5: Solve for x
    x = 116.65/10.85
  6. Step 6: Final answer
    x = 10.75

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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.