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Finding the Fourth Proportional to 989.68, 1,365.48 and 640.48

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Solution

The fourth proportional to 989.68, 1,365.48 and 640.48 is: 883.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.68 : 1,365.48 = 640.48 : x
  2. Step 2: Convert to fraction form
    989.68/1,365.48 = 640.48/x
  3. Step 3: Cross multiply
    989.68x = 1,365.48 × 640.48
  4. Step 4: Simplify right side
    989.68x = 874,562.63
  5. Step 5: Solve for x
    x = 874,562.63/989.68
  6. Step 6: Final answer
    x = 883.68

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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.