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Finding the Fourth Proportional to 991.84, 1,370 and 860.80

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Solution

The fourth proportional to 991.84, 1,370 and 860.80 is: 1,189.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.84 : 1,370 = 860.80 : x
  2. Step 2: Convert to fraction form
    991.84/1,370 = 860.80/x
  3. Step 3: Cross multiply
    991.84x = 1,370 × 860.80
  4. Step 4: Simplify right side
    991.84x = 1,179,296
  5. Step 5: Solve for x
    x = 1,179,296/991.84
  6. Step 6: Final answer
    x = 1,189.00

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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.