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Finding the Fourth Proportional to 99.36, 136.80 and 90

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Solution

The fourth proportional to 99.36, 136.80 and 90 is: 123.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.36 : 136.80 = 90 : x
  2. Step 2: Convert to fraction form
    99.36/136.80 = 90/x
  3. Step 3: Cross multiply
    99.36x = 136.80 × 90
  4. Step 4: Simplify right side
    99.36x = 12,312.00
  5. Step 5: Solve for x
    x = 12,312.00/99.36
  6. Step 6: Final answer
    x = 123.91

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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.