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Finding the Fourth Proportional to 117.21, 161.64 and 99.78

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Solution

The fourth proportional to 117.21, 161.64 and 99.78 is: 137.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    117.21 : 161.64 = 99.78 : x
  2. Step 2: Convert to fraction form
    117.21/161.64 = 99.78/x
  3. Step 3: Cross multiply
    117.21x = 161.64 × 99.78
  4. Step 4: Simplify right side
    117.21x = 16,128.44
  5. Step 5: Solve for x
    x = 16,128.44/117.21
  6. Step 6: Final answer
    x = 137.60

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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.