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Finding the Fourth Proportional to 1,115.78, 1,680.01 and 986.58

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Solution

The fourth proportional to 1,115.78, 1,680.01 and 986.58 is: 1,485.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,115.78 : 1,680.01 = 986.58 : x
  2. Step 2: Convert to fraction form
    1,115.78/1,680.01 = 986.58/x
  3. Step 3: Cross multiply
    1,115.78x = 1,680.01 × 986.58
  4. Step 4: Simplify right side
    1,115.78x = 1,657,461.80
  5. Step 5: Solve for x
    x = 1,657,461.80/1,115.78
  6. Step 6: Final answer
    x = 1,485.48

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.