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Finding the Fourth Proportional to 760.40, 1,137.72 and 720.80

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Solution

The fourth proportional to 760.40, 1,137.72 and 720.80 is: 1,078.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    760.40 : 1,137.72 = 720.80 : x
  2. Step 2: Convert to fraction form
    760.40/1,137.72 = 720.80/x
  3. Step 3: Cross multiply
    760.40x = 1,137.72 × 720.80
  4. Step 4: Simplify right side
    760.40x = 820,068.58
  5. Step 5: Solve for x
    x = 820,068.58/760.40
  6. Step 6: Final answer
    x = 1,078.47

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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.