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Finding the Fourth Proportional to 1,407.78, 1,942.80 and 786.78

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Solution

The fourth proportional to 1,407.78, 1,942.80 and 786.78 is: 1,085.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,407.78 : 1,942.80 = 786.78 : x
  2. Step 2: Convert to fraction form
    1,407.78/1,942.80 = 786.78/x
  3. Step 3: Cross multiply
    1,407.78x = 1,942.80 × 786.78
  4. Step 4: Simplify right side
    1,407.78x = 1,528,556.18
  5. Step 5: Solve for x
    x = 1,528,556.18/1,407.78
  6. Step 6: Final answer
    x = 1,085.79

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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.