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Finding the Fourth Proportional to 993.68, 1,369.99 and 639

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Solution

The fourth proportional to 993.68, 1,369.99 and 639 is: 880.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    993.68 : 1,369.99 = 639 : x
  2. Step 2: Convert to fraction form
    993.68/1,369.99 = 639/x
  3. Step 3: Cross multiply
    993.68x = 1,369.99 × 639
  4. Step 4: Simplify right side
    993.68x = 875,424.41
  5. Step 5: Solve for x
    x = 875,424.41/993.68
  6. Step 6: Final answer
    x = 880.99

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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.