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Finding the Fourth Proportional to 911.25, 1,257.63 and 518.40

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Solution

The fourth proportional to 911.25, 1,257.63 and 518.40 is: 715.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    911.25 : 1,257.63 = 518.40 : x
  2. Step 2: Convert to fraction form
    911.25/1,257.63 = 518.40/x
  3. Step 3: Cross multiply
    911.25x = 1,257.63 × 518.40
  4. Step 4: Simplify right side
    911.25x = 651,953.45
  5. Step 5: Solve for x
    x = 651,953.45/911.25
  6. Step 6: Final answer
    x = 715.45

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.