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Finding the Fourth Proportional to 989.77, 1,485.17 and 643.02

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Solution

The fourth proportional to 989.77, 1,485.17 and 643.02 is: 964.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.77 : 1,485.17 = 643.02 : x
  2. Step 2: Convert to fraction form
    989.77/1,485.17 = 643.02/x
  3. Step 3: Cross multiply
    989.77x = 1,485.17 × 643.02
  4. Step 4: Simplify right side
    989.77x = 954,993.21
  5. Step 5: Solve for x
    x = 954,993.21/989.77
  6. Step 6: Final answer
    x = 964.87

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.