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Finding the Fourth Proportional to 1,282.20, 1,769.40 and 715

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Solution

The fourth proportional to 1,282.20, 1,769.40 and 715 is: 986.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,282.20 : 1,769.40 = 715 : x
  2. Step 2: Convert to fraction form
    1,282.20/1,769.40 = 715/x
  3. Step 3: Cross multiply
    1,282.20x = 1,769.40 × 715
  4. Step 4: Simplify right side
    1,282.20x = 1,265,121
  5. Step 5: Solve for x
    x = 1,265,121/1,282.20
  6. Step 6: Final answer
    x = 986.68

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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.