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Finding the Fourth Proportional to 1,287.70, 1,776.96 and 728.18

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Solution

The fourth proportional to 1,287.70, 1,776.96 and 728.18 is: 1,004.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.70 : 1,776.96 = 728.18 : x
  2. Step 2: Convert to fraction form
    1,287.70/1,776.96 = 728.18/x
  3. Step 3: Cross multiply
    1,287.70x = 1,776.96 × 728.18
  4. Step 4: Simplify right side
    1,287.70x = 1,293,946.73
  5. Step 5: Solve for x
    x = 1,293,946.73/1,287.70
  6. Step 6: Final answer
    x = 1,004.85

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1.5x scale

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.