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Finding the Fourth Proportional to 772.64, 1,064.40 and 639

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Solution

The fourth proportional to 772.64, 1,064.40 and 639 is: 880.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    772.64 : 1,064.40 = 639 : x
  2. Step 2: Convert to fraction form
    772.64/1,064.40 = 639/x
  3. Step 3: Cross multiply
    772.64x = 1,064.40 × 639
  4. Step 4: Simplify right side
    772.64x = 680,151.60
  5. Step 5: Solve for x
    x = 680,151.60/772.64
  6. Step 6: Final answer
    x = 880.30

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.