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Finding the Fourth Proportional to 760.80, 1,139.94 and 639.12

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Solution

The fourth proportional to 760.80, 1,139.94 and 639.12 is: 957.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    760.80 : 1,139.94 = 639.12 : x
  2. Step 2: Convert to fraction form
    760.80/1,139.94 = 639.12/x
  3. Step 3: Cross multiply
    760.80x = 1,139.94 × 639.12
  4. Step 4: Simplify right side
    760.80x = 728,558.45
  5. Step 5: Solve for x
    x = 728,558.45/760.80
  6. Step 6: Final answer
    x = 957.62

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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.