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Finding the Fourth Proportional to 690.84, 1,036.78 and 280.20

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Solution

The fourth proportional to 690.84, 1,036.78 and 280.20 is: 420.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.84 : 1,036.78 = 280.20 : x
  2. Step 2: Convert to fraction form
    690.84/1,036.78 = 280.20/x
  3. Step 3: Cross multiply
    690.84x = 1,036.78 × 280.20
  4. Step 4: Simplify right side
    690.84x = 290,505.76
  5. Step 5: Solve for x
    x = 290,505.76/690.84
  6. Step 6: Final answer
    x = 420.51

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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.