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Finding the Fourth Proportional to 690.50, 1,036.12 and 257.78

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Solution

The fourth proportional to 690.50, 1,036.12 and 257.78 is: 386.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.50 : 1,036.12 = 257.78 : x
  2. Step 2: Convert to fraction form
    690.50/1,036.12 = 257.78/x
  3. Step 3: Cross multiply
    690.50x = 1,036.12 × 257.78
  4. Step 4: Simplify right side
    690.50x = 267,091.01
  5. Step 5: Solve for x
    x = 267,091.01/690.50
  6. Step 6: Final answer
    x = 386.81

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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.