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Finding the Fourth Proportional to 780.90, 1,069.21 and 778.18

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Solution

The fourth proportional to 780.90, 1,069.21 and 778.18 is: 1,065.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.90 : 1,069.21 = 778.18 : x
  2. Step 2: Convert to fraction form
    780.90/1,069.21 = 778.18/x
  3. Step 3: Cross multiply
    780.90x = 1,069.21 × 778.18
  4. Step 4: Simplify right side
    780.90x = 832,037.84
  5. Step 5: Solve for x
    x = 832,037.84/780.90
  6. Step 6: Final answer
    x = 1,065.49

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.