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Finding the Fourth Proportional to 1,188.72, 1,639.68 and 858

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Solution

The fourth proportional to 1,188.72, 1,639.68 and 858 is: 1,183.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,188.72 : 1,639.68 = 858 : x
  2. Step 2: Convert to fraction form
    1,188.72/1,639.68 = 858/x
  3. Step 3: Cross multiply
    1,188.72x = 1,639.68 × 858
  4. Step 4: Simplify right side
    1,188.72x = 1,406,845.44
  5. Step 5: Solve for x
    x = 1,406,845.44/1,188.72
  6. Step 6: Final answer
    x = 1,183.50

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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.