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Finding the Fourth Proportional to 957.27, 1,321.28 and 643.20

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Solution

The fourth proportional to 957.27, 1,321.28 and 643.20 is: 887.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    957.27 : 1,321.28 = 643.20 : x
  2. Step 2: Convert to fraction form
    957.27/1,321.28 = 643.20/x
  3. Step 3: Cross multiply
    957.27x = 1,321.28 × 643.20
  4. Step 4: Simplify right side
    957.27x = 849,847.30
  5. Step 5: Solve for x
    x = 849,847.30/957.27
  6. Step 6: Final answer
    x = 887.78

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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.