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Finding the Fourth Proportional to 859.17, 1,287.75 and 420.63

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Solution

The fourth proportional to 859.17, 1,287.75 and 420.63 is: 630.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    859.17 : 1,287.75 = 420.63 : x
  2. Step 2: Convert to fraction form
    859.17/1,287.75 = 420.63/x
  3. Step 3: Cross multiply
    859.17x = 1,287.75 × 420.63
  4. Step 4: Simplify right side
    859.17x = 541,666.28
  5. Step 5: Solve for x
    x = 541,666.28/859.17
  6. Step 6: Final answer
    x = 630.45

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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.