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Finding the Fourth Proportional to 1,187.79, 1,639.26 and 715.83

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Solution

The fourth proportional to 1,187.79, 1,639.26 and 715.83 is: 987.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.79 : 1,639.26 = 715.83 : x
  2. Step 2: Convert to fraction form
    1,187.79/1,639.26 = 715.83/x
  3. Step 3: Cross multiply
    1,187.79x = 1,639.26 × 715.83
  4. Step 4: Simplify right side
    1,187.79x = 1,173,431.49
  5. Step 5: Solve for x
    x = 1,173,431.49/1,187.79
  6. Step 6: Final answer
    x = 987.91

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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.