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Finding the Fourth Proportional to 1,392.58, 2,087.40 and 661.28

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Solution

The fourth proportional to 1,392.58, 2,087.40 and 661.28 is: 991.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,392.58 : 2,087.40 = 661.28 : x
  2. Step 2: Convert to fraction form
    1,392.58/2,087.40 = 661.28/x
  3. Step 3: Cross multiply
    1,392.58x = 2,087.40 × 661.28
  4. Step 4: Simplify right side
    1,392.58x = 1,380,355.87
  5. Step 5: Solve for x
    x = 1,380,355.87/1,392.58
  6. Step 6: Final answer
    x = 991.22

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.