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Finding the Fourth Proportional to 859.80, 1,290.12 and 312.12

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Solution

The fourth proportional to 859.80, 1,290.12 and 312.12 is: 468.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    859.80 : 1,290.12 = 312.12 : x
  2. Step 2: Convert to fraction form
    859.80/1,290.12 = 312.12/x
  3. Step 3: Cross multiply
    859.80x = 1,290.12 × 312.12
  4. Step 4: Simplify right side
    859.80x = 402,672.25
  5. Step 5: Solve for x
    x = 402,672.25/859.80
  6. Step 6: Final answer
    x = 468.33

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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.