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Finding the Fourth Proportional to 991.32, 1,368.50 and 678.20

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Solution

The fourth proportional to 991.32, 1,368.50 and 678.20 is: 936.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.32 : 1,368.50 = 678.20 : x
  2. Step 2: Convert to fraction form
    991.32/1,368.50 = 678.20/x
  3. Step 3: Cross multiply
    991.32x = 1,368.50 × 678.20
  4. Step 4: Simplify right side
    991.32x = 928,116.70
  5. Step 5: Solve for x
    x = 928,116.70/991.32
  6. Step 6: Final answer
    x = 936.24

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1.5x scale

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.