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Finding the Fourth Proportional to 989.64, 1,365.12 and 640.53

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Solution

The fourth proportional to 989.64, 1,365.12 and 640.53 is: 883.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.64 : 1,365.12 = 640.53 : x
  2. Step 2: Convert to fraction form
    989.64/1,365.12 = 640.53/x
  3. Step 3: Cross multiply
    989.64x = 1,365.12 × 640.53
  4. Step 4: Simplify right side
    989.64x = 874,400.31
  5. Step 5: Solve for x
    x = 874,400.31/989.64
  6. Step 6: Final answer
    x = 883.55

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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.