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Finding the Fourth Proportional to 815.70, 1,215.92 and 788.70

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Solution

The fourth proportional to 815.70, 1,215.92 and 788.70 is: 1,175.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.70 : 1,215.92 = 788.70 : x
  2. Step 2: Convert to fraction form
    815.70/1,215.92 = 788.70/x
  3. Step 3: Cross multiply
    815.70x = 1,215.92 × 788.70
  4. Step 4: Simplify right side
    815.70x = 958,996.10
  5. Step 5: Solve for x
    x = 958,996.10/815.70
  6. Step 6: Final answer
    x = 1,175.67

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.