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Finding the Fourth Proportional to 993.12, 1,369.20 and 643.68

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Solution

The fourth proportional to 993.12, 1,369.20 and 643.68 is: 887.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    993.12 : 1,369.20 = 643.68 : x
  2. Step 2: Convert to fraction form
    993.12/1,369.20 = 643.68/x
  3. Step 3: Cross multiply
    993.12x = 1,369.20 × 643.68
  4. Step 4: Simplify right side
    993.12x = 881,326.66
  5. Step 5: Solve for x
    x = 881,326.66/993.12
  6. Step 6: Final answer
    x = 887.43

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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.