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Finding the Fourth Proportional to 1,011.65, 1,391.89 and 790.21

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Solution

The fourth proportional to 1,011.65, 1,391.89 and 790.21 is: 1,087.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,011.65 : 1,391.89 = 790.21 : x
  2. Step 2: Convert to fraction form
    1,011.65/1,391.89 = 790.21/x
  3. Step 3: Cross multiply
    1,011.65x = 1,391.89 × 790.21
  4. Step 4: Simplify right side
    1,011.65x = 1,099,885.40
  5. Step 5: Solve for x
    x = 1,099,885.40/1,011.65
  6. Step 6: Final answer
    x = 1,087.22

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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.