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Finding the Fourth Proportional to 11.55, 15.90 and 9.99

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Solution

The fourth proportional to 11.55, 15.90 and 9.99 is: 13.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    11.55 : 15.90 = 9.99 : x
  2. Step 2: Convert to fraction form
    11.55/15.90 = 9.99/x
  3. Step 3: Cross multiply
    11.55x = 15.90 × 9.99
  4. Step 4: Simplify right side
    11.55x = 158.84
  5. Step 5: Solve for x
    x = 158.84/11.55
  6. Step 6: Final answer
    x = 13.75

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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.