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Finding the Fourth Proportional to 1,019.78, 1,407.08 and 665.75

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Solution

The fourth proportional to 1,019.78, 1,407.08 and 665.75 is: 918.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,019.78 : 1,407.08 = 665.75 : x
  2. Step 2: Convert to fraction form
    1,019.78/1,407.08 = 665.75/x
  3. Step 3: Cross multiply
    1,019.78x = 1,407.08 × 665.75
  4. Step 4: Simplify right side
    1,019.78x = 936,763.51
  5. Step 5: Solve for x
    x = 936,763.51/1,019.78
  6. Step 6: Final answer
    x = 918.59

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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.