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Finding the Fourth Proportional to 987.49, 1,362.81 and 639.19

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Solution

The fourth proportional to 987.49, 1,362.81 and 639.19 is: 882.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.49 : 1,362.81 = 639.19 : x
  2. Step 2: Convert to fraction form
    987.49/1,362.81 = 639.19/x
  3. Step 3: Cross multiply
    987.49x = 1,362.81 × 639.19
  4. Step 4: Simplify right side
    987.49x = 871,084.51
  5. Step 5: Solve for x
    x = 871,084.51/987.49
  6. Step 6: Final answer
    x = 882.12

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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.