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Finding the Fourth Proportional to 1,187.26, 1,638.90 and 1,020.80

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Solution

The fourth proportional to 1,187.26, 1,638.90 and 1,020.80 is: 1,409.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.26 : 1,638.90 = 1,020.80 : x
  2. Step 2: Convert to fraction form
    1,187.26/1,638.90 = 1,020.80/x
  3. Step 3: Cross multiply
    1,187.26x = 1,638.90 × 1,020.80
  4. Step 4: Simplify right side
    1,187.26x = 1,672,993.22
  5. Step 5: Solve for x
    x = 1,672,993.22/1,187.26
  6. Step 6: Final answer
    x = 1,409.12

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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.