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Finding the Fourth Proportional to 791.40, 1,090.62 and 687.72

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Solution

The fourth proportional to 791.40, 1,090.62 and 687.72 is: 947.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    791.40 : 1,090.62 = 687.72 : x
  2. Step 2: Convert to fraction form
    791.40/1,090.62 = 687.72/x
  3. Step 3: Cross multiply
    791.40x = 1,090.62 × 687.72
  4. Step 4: Simplify right side
    791.40x = 750,041.19
  5. Step 5: Solve for x
    x = 750,041.19/791.40
  6. Step 6: Final answer
    x = 947.74

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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.