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Finding the Fourth Proportional to 1,187.89, 1,639.29 and 663.91

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Solution

The fourth proportional to 1,187.89, 1,639.29 and 663.91 is: 916.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.89 : 1,639.29 = 663.91 : x
  2. Step 2: Convert to fraction form
    1,187.89/1,639.29 = 663.91/x
  3. Step 3: Cross multiply
    1,187.89x = 1,639.29 × 663.91
  4. Step 4: Simplify right side
    1,187.89x = 1,088,341.02
  5. Step 5: Solve for x
    x = 1,088,341.02/1,187.89
  6. Step 6: Final answer
    x = 916.20

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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.