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Finding the Fourth Proportional to 1,186.30, 1,780.80 and 638.20

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Solution

The fourth proportional to 1,186.30, 1,780.80 and 638.20 is: 958.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,186.30 : 1,780.80 = 638.20 : x
  2. Step 2: Convert to fraction form
    1,186.30/1,780.80 = 638.20/x
  3. Step 3: Cross multiply
    1,186.30x = 1,780.80 × 638.20
  4. Step 4: Simplify right side
    1,186.30x = 1,136,506.56
  5. Step 5: Solve for x
    x = 1,136,506.56/1,186.30
  6. Step 6: Final answer
    x = 958.03

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.