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Finding the Fourth Proportional to 858.30, 1,287.45 and 628.80

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Solution

The fourth proportional to 858.30, 1,287.45 and 628.80 is: 943.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.30 : 1,287.45 = 628.80 : x
  2. Step 2: Convert to fraction form
    858.30/1,287.45 = 628.80/x
  3. Step 3: Cross multiply
    858.30x = 1,287.45 × 628.80
  4. Step 4: Simplify right side
    858.30x = 809,548.56
  5. Step 5: Solve for x
    x = 809,548.56/858.30
  6. Step 6: Final answer
    x = 943.20

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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.