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Finding the Fourth Proportional to 99.70, 137.21 and 90.50

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Solution

The fourth proportional to 99.70, 137.21 and 90.50 is: 124.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.70 : 137.21 = 90.50 : x
  2. Step 2: Convert to fraction form
    99.70/137.21 = 90.50/x
  3. Step 3: Cross multiply
    99.70x = 137.21 × 90.50
  4. Step 4: Simplify right side
    99.70x = 12,417.51
  5. Step 5: Solve for x
    x = 12,417.51/99.70
  6. Step 6: Final answer
    x = 124.55

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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.