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Finding the Fourth Proportional to 1,221.61, 1,685.42 and 779.65

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Solution

The fourth proportional to 1,221.61, 1,685.42 and 779.65 is: 1,075.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.61 : 1,685.42 = 779.65 : x
  2. Step 2: Convert to fraction form
    1,221.61/1,685.42 = 779.65/x
  3. Step 3: Cross multiply
    1,221.61x = 1,685.42 × 779.65
  4. Step 4: Simplify right side
    1,221.61x = 1,314,038.35
  5. Step 5: Solve for x
    x = 1,314,038.35/1,221.61
  6. Step 6: Final answer
    x = 1,075.66

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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.