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Finding the Fourth Proportional to 869.72, 1,299.44 and 646.40

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Solution

The fourth proportional to 869.72, 1,299.44 and 646.40 is: 965.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    869.72 : 1,299.44 = 646.40 : x
  2. Step 2: Convert to fraction form
    869.72/1,299.44 = 646.40/x
  3. Step 3: Cross multiply
    869.72x = 1,299.44 × 646.40
  4. Step 4: Simplify right side
    869.72x = 839,948.29
  5. Step 5: Solve for x
    x = 839,948.29/869.72
  6. Step 6: Final answer
    x = 965.77

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.