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Finding the Fourth Proportional to 690.45, 1,035.36 and 257.55

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Solution

The fourth proportional to 690.45, 1,035.36 and 257.55 is: 386.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.45 : 1,035.36 = 257.55 : x
  2. Step 2: Convert to fraction form
    690.45/1,035.36 = 257.55/x
  3. Step 3: Cross multiply
    690.45x = 1,035.36 × 257.55
  4. Step 4: Simplify right side
    690.45x = 266,656.97
  5. Step 5: Solve for x
    x = 266,656.97/690.45
  6. Step 6: Final answer
    x = 386.21

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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.