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Finding the Fourth Proportional to 989.04, 1,364.86 and 639.72

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Solution

The fourth proportional to 989.04, 1,364.86 and 639.72 is: 882.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.04 : 1,364.86 = 639.72 : x
  2. Step 2: Convert to fraction form
    989.04/1,364.86 = 639.72/x
  3. Step 3: Cross multiply
    989.04x = 1,364.86 × 639.72
  4. Step 4: Simplify right side
    989.04x = 873,128.24
  5. Step 5: Solve for x
    x = 873,128.24/989.04
  6. Step 6: Final answer
    x = 882.80

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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.