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Finding the Fourth Proportional to 859.49, 1,290.75 and 640.18

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Solution

The fourth proportional to 859.49, 1,290.75 and 640.18 is: 961.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    859.49 : 1,290.75 = 640.18 : x
  2. Step 2: Convert to fraction form
    859.49/1,290.75 = 640.18/x
  3. Step 3: Cross multiply
    859.49x = 1,290.75 × 640.18
  4. Step 4: Simplify right side
    859.49x = 826,312.34
  5. Step 5: Solve for x
    x = 826,312.34/859.49
  6. Step 6: Final answer
    x = 961.40

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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.