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Finding the Fourth Proportional to 869.90, 1,198.87 and 687.42

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Solution

The fourth proportional to 869.90, 1,198.87 and 687.42 is: 947.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    869.90 : 1,198.87 = 687.42 : x
  2. Step 2: Convert to fraction form
    869.90/1,198.87 = 687.42/x
  3. Step 3: Cross multiply
    869.90x = 1,198.87 × 687.42
  4. Step 4: Simplify right side
    869.90x = 824,127.22
  5. Step 5: Solve for x
    x = 824,127.22/869.90
  6. Step 6: Final answer
    x = 947.38

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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.