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Finding the Fourth Proportional to 980.70, 1,351.05 and 840.36

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Solution

The fourth proportional to 980.70, 1,351.05 and 840.36 is: 1,157.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    980.70 : 1,351.05 = 840.36 : x
  2. Step 2: Convert to fraction form
    980.70/1,351.05 = 840.36/x
  3. Step 3: Cross multiply
    980.70x = 1,351.05 × 840.36
  4. Step 4: Simplify right side
    980.70x = 1,135,368.38
  5. Step 5: Solve for x
    x = 1,135,368.38/980.70
  6. Step 6: Final answer
    x = 1,157.71

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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.