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Finding the Fourth Proportional to 1,187.28, 1,638.36 and 715.10

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Solution

The fourth proportional to 1,187.28, 1,638.36 and 715.10 is: 986.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.28 : 1,638.36 = 715.10 : x
  2. Step 2: Convert to fraction form
    1,187.28/1,638.36 = 715.10/x
  3. Step 3: Cross multiply
    1,187.28x = 1,638.36 × 715.10
  4. Step 4: Simplify right side
    1,187.28x = 1,171,583.04
  5. Step 5: Solve for x
    x = 1,171,583.04/1,187.28
  6. Step 6: Final answer
    x = 986.78

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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.