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Finding the Fourth Proportional to 780.03, 1,074.78 and 639.68

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Solution

The fourth proportional to 780.03, 1,074.78 and 639.68 is: 881.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.03 : 1,074.78 = 639.68 : x
  2. Step 2: Convert to fraction form
    780.03/1,074.78 = 639.68/x
  3. Step 3: Cross multiply
    780.03x = 1,074.78 × 639.68
  4. Step 4: Simplify right side
    780.03x = 687,509.90
  5. Step 5: Solve for x
    x = 687,509.90/780.03
  6. Step 6: Final answer
    x = 881.39

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1.5x scale

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.