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Finding the Fourth Proportional to 1,409, 2,113.78 and 639.50

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Solution

The fourth proportional to 1,409, 2,113.78 and 639.50 is: 959.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,409 : 2,113.78 = 639.50 : x
  2. Step 2: Convert to fraction form
    1,409/2,113.78 = 639.50/x
  3. Step 3: Cross multiply
    1,409x = 2,113.78 × 639.50
  4. Step 4: Simplify right side
    1,409x = 1,351,762.31
  5. Step 5: Solve for x
    x = 1,351,762.31/1,409
  6. Step 6: Final answer
    x = 959.38

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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.