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Finding the Fourth Proportional to 1,205, 1,807.78 and 619.78

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Solution

The fourth proportional to 1,205, 1,807.78 and 619.78 is: 929.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,205 : 1,807.78 = 619.78 : x
  2. Step 2: Convert to fraction form
    1,205/1,807.78 = 619.78/x
  3. Step 3: Cross multiply
    1,205x = 1,807.78 × 619.78
  4. Step 4: Simplify right side
    1,205x = 1,120,425.89
  5. Step 5: Solve for x
    x = 1,120,425.89/1,205
  6. Step 6: Final answer
    x = 929.81

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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.