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Finding the Fourth Proportional to 991.19, 1,368.41 and 688.79

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Solution

The fourth proportional to 991.19, 1,368.41 and 688.79 is: 950.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.19 : 1,368.41 = 688.79 : x
  2. Step 2: Convert to fraction form
    991.19/1,368.41 = 688.79/x
  3. Step 3: Cross multiply
    991.19x = 1,368.41 × 688.79
  4. Step 4: Simplify right side
    991.19x = 942,547.10
  5. Step 5: Solve for x
    x = 942,547.10/991.19
  6. Step 6: Final answer
    x = 950.92

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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.