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Finding the Fourth Proportional to 1,419.99, 2,128.35 and 639.15

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Solution

The fourth proportional to 1,419.99, 2,128.35 and 639.15 is: 957.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,419.99 : 2,128.35 = 639.15 : x
  2. Step 2: Convert to fraction form
    1,419.99/2,128.35 = 639.15/x
  3. Step 3: Cross multiply
    1,419.99x = 2,128.35 × 639.15
  4. Step 4: Simplify right side
    1,419.99x = 1,360,334.90
  5. Step 5: Solve for x
    x = 1,360,334.90/1,419.99
  6. Step 6: Final answer
    x = 957.99

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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.