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Finding the Fourth Proportional to 857.16, 1,285.80 and 279.84

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Solution

The fourth proportional to 857.16, 1,285.80 and 279.84 is: 419.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.16 : 1,285.80 = 279.84 : x
  2. Step 2: Convert to fraction form
    857.16/1,285.80 = 279.84/x
  3. Step 3: Cross multiply
    857.16x = 1,285.80 × 279.84
  4. Step 4: Simplify right side
    857.16x = 359,818.27
  5. Step 5: Solve for x
    x = 359,818.27/857.16
  6. Step 6: Final answer
    x = 419.78

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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.