Finding the Fourth Proportional to 100.68, 138.74 and 78.81
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Solution
The fourth proportional to 100.68, 138.74 and 78.81 is: 108.60
Step by Step Solution
- Step 1: Write the proportion equation
100.68 : 138.74 = 78.81 : x - Step 2: Convert to fraction form
100.68/138.74 = 78.81/x - Step 3: Cross multiply
100.68x = 138.74 × 78.81 - Step 4: Simplify right side
100.68x = 10,933.71 - Step 5: Solve for x
x = 10,933.71/100.68 - Step 6: Final answer
x = 108.60
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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.