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Finding the Fourth Proportional to 429.21, 643.80 and 121.10

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Solution

The fourth proportional to 429.21, 643.80 and 121.10 is: 181.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.21 : 643.80 = 121.10 : x
  2. Step 2: Convert to fraction form
    429.21/643.80 = 121.10/x
  3. Step 3: Cross multiply
    429.21x = 643.80 × 121.10
  4. Step 4: Simplify right side
    429.21x = 77,960.96
  5. Step 5: Solve for x
    x = 77,960.96/429.21
  6. Step 6: Final answer
    x = 181.64

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.