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Finding the Fourth Proportional to 1,288.79, 1,778.37 and 721.65

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Solution

The fourth proportional to 1,288.79, 1,778.37 and 721.65 is: 995.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,288.79 : 1,778.37 = 721.65 : x
  2. Step 2: Convert to fraction form
    1,288.79/1,778.37 = 721.65/x
  3. Step 3: Cross multiply
    1,288.79x = 1,778.37 × 721.65
  4. Step 4: Simplify right side
    1,288.79x = 1,283,370.09
  5. Step 5: Solve for x
    x = 1,283,370.09/1,288.79
  6. Step 6: Final answer
    x = 995.80

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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.