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Finding the Fourth Proportional to 1,278.36, 1,913.42 and 661.22

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Solution

The fourth proportional to 1,278.36, 1,913.42 and 661.22 is: 989.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.36 : 1,913.42 = 661.22 : x
  2. Step 2: Convert to fraction form
    1,278.36/1,913.42 = 661.22/x
  3. Step 3: Cross multiply
    1,278.36x = 1,913.42 × 661.22
  4. Step 4: Simplify right side
    1,278.36x = 1,265,178.70
  5. Step 5: Solve for x
    x = 1,265,178.70/1,278.36
  6. Step 6: Final answer
    x = 989.69

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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.