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Finding the Fourth Proportional to 1,187.78, 1,639.10 and 690.39

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Solution

The fourth proportional to 1,187.78, 1,639.10 and 690.39 is: 952.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.78 : 1,639.10 = 690.39 : x
  2. Step 2: Convert to fraction form
    1,187.78/1,639.10 = 690.39/x
  3. Step 3: Cross multiply
    1,187.78x = 1,639.10 × 690.39
  4. Step 4: Simplify right side
    1,187.78x = 1,131,606.60
  5. Step 5: Solve for x
    x = 1,131,606.60/1,187.78
  6. Step 6: Final answer
    x = 952.71

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1.5x scale

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.