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Finding the Fourth Proportional to 780.30, 1,075.80 and 640.26

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Solution

The fourth proportional to 780.30, 1,075.80 and 640.26 is: 882.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.30 : 1,075.80 = 640.26 : x
  2. Step 2: Convert to fraction form
    780.30/1,075.80 = 640.26/x
  3. Step 3: Cross multiply
    780.30x = 1,075.80 × 640.26
  4. Step 4: Simplify right side
    780.30x = 688,791.71
  5. Step 5: Solve for x
    x = 688,791.71/780.30
  6. Step 6: Final answer
    x = 882.73

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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.