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Finding the Fourth Proportional to 1,298.32, 1,789.80 and 987.28

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Solution

The fourth proportional to 1,298.32, 1,789.80 and 987.28 is: 1,361.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,298.32 : 1,789.80 = 987.28 : x
  2. Step 2: Convert to fraction form
    1,298.32/1,789.80 = 987.28/x
  3. Step 3: Cross multiply
    1,298.32x = 1,789.80 × 987.28
  4. Step 4: Simplify right side
    1,298.32x = 1,767,033.74
  5. Step 5: Solve for x
    x = 1,767,033.74/1,298.32
  6. Step 6: Final answer
    x = 1,361.02

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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.