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Finding the Fourth Proportional to 857.76, 1,182.96 and 780

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Solution

The fourth proportional to 857.76, 1,182.96 and 780 is: 1,075.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.76 : 1,182.96 = 780 : x
  2. Step 2: Convert to fraction form
    857.76/1,182.96 = 780/x
  3. Step 3: Cross multiply
    857.76x = 1,182.96 × 780
  4. Step 4: Simplify right side
    857.76x = 922,708.80
  5. Step 5: Solve for x
    x = 922,708.80/857.76
  6. Step 6: Final answer
    x = 1,075.72

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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.