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Finding the Fourth Proportional to 1,187.76, 1,638.30 and 783.76

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Solution

The fourth proportional to 1,187.76, 1,638.30 and 783.76 is: 1,081.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.76 : 1,638.30 = 783.76 : x
  2. Step 2: Convert to fraction form
    1,187.76/1,638.30 = 783.76/x
  3. Step 3: Cross multiply
    1,187.76x = 1,638.30 × 783.76
  4. Step 4: Simplify right side
    1,187.76x = 1,284,034.01
  5. Step 5: Solve for x
    x = 1,284,034.01/1,187.76
  6. Step 6: Final answer
    x = 1,081.06

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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.