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Finding the Fourth Proportional to 1,938.40, 2,907.60 and 639.70

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Solution

The fourth proportional to 1,938.40, 2,907.60 and 639.70 is: 959.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,938.40 : 2,907.60 = 639.70 : x
  2. Step 2: Convert to fraction form
    1,938.40/2,907.60 = 639.70/x
  3. Step 3: Cross multiply
    1,938.40x = 2,907.60 × 639.70
  4. Step 4: Simplify right side
    1,938.40x = 1,859,991.72
  5. Step 5: Solve for x
    x = 1,859,991.72/1,938.40
  6. Step 6: Final answer
    x = 959.55

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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.