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Finding the Fourth Proportional to 858.80, 1,288.20 and 853.40

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Solution

The fourth proportional to 858.80, 1,288.20 and 853.40 is: 1,280.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.80 : 1,288.20 = 853.40 : x
  2. Step 2: Convert to fraction form
    858.80/1,288.20 = 853.40/x
  3. Step 3: Cross multiply
    858.80x = 1,288.20 × 853.40
  4. Step 4: Simplify right side
    858.80x = 1,099,349.88
  5. Step 5: Solve for x
    x = 1,099,349.88/858.80
  6. Step 6: Final answer
    x = 1,280.10

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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.