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Finding the Fourth Proportional to 786.71, 1,080.79 and 638.89

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Solution

The fourth proportional to 786.71, 1,080.79 and 638.89 is: 877.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    786.71 : 1,080.79 = 638.89 : x
  2. Step 2: Convert to fraction form
    786.71/1,080.79 = 638.89/x
  3. Step 3: Cross multiply
    786.71x = 1,080.79 × 638.89
  4. Step 4: Simplify right side
    786.71x = 690,505.22
  5. Step 5: Solve for x
    x = 690,505.22/786.71
  6. Step 6: Final answer
    x = 877.71

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.