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Finding the Fourth Proportional to 1,420.87, 2,129.51 and 640.04

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Solution

The fourth proportional to 1,420.87, 2,129.51 and 640.04 is: 959.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,420.87 : 2,129.51 = 640.04 : x
  2. Step 2: Convert to fraction form
    1,420.87/2,129.51 = 640.04/x
  3. Step 3: Cross multiply
    1,420.87x = 2,129.51 × 640.04
  4. Step 4: Simplify right side
    1,420.87x = 1,362,971.58
  5. Step 5: Solve for x
    x = 1,362,971.58/1,420.87
  6. Step 6: Final answer
    x = 959.25

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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.