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Finding the Fourth Proportional to 839.99, 1,259.80 and 319.81

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Solution

The fourth proportional to 839.99, 1,259.80 and 319.81 is: 479.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.99 : 1,259.80 = 319.81 : x
  2. Step 2: Convert to fraction form
    839.99/1,259.80 = 319.81/x
  3. Step 3: Cross multiply
    839.99x = 1,259.80 × 319.81
  4. Step 4: Simplify right side
    839.99x = 402,892.69
  5. Step 5: Solve for x
    x = 402,892.69/839.99
  6. Step 6: Final answer
    x = 479.64

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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.