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Finding the Fourth Proportional to 790.71, 1,091.69 and 643.69

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Solution

The fourth proportional to 790.71, 1,091.69 and 643.69 is: 888.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    790.71 : 1,091.69 = 643.69 : x
  2. Step 2: Convert to fraction form
    790.71/1,091.69 = 643.69/x
  3. Step 3: Cross multiply
    790.71x = 1,091.69 × 643.69
  4. Step 4: Simplify right side
    790.71x = 702,706.72
  5. Step 5: Solve for x
    x = 702,706.72/790.71
  6. Step 6: Final answer
    x = 888.71

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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.