Finding the Fourth Proportional to 81.20, 121.65 and 72.75
Calculator
Solution
The fourth proportional to 81.20, 121.65 and 72.75 is: 108.99
Step by Step Solution
- Step 1: Write the proportion equation
81.20 : 121.65 = 72.75 : x - Step 2: Convert to fraction form
81.20/121.65 = 72.75/x - Step 3: Cross multiply
81.20x = 121.65 × 72.75 - Step 4: Simplify right side
81.20x = 8,849.95 - Step 5: Solve for x
x = 8,849.95/81.20 - Step 6: Final answer
x = 108.99
Related Problems
Find fourth proportional to 40.60, 60.83 and 36.37
Half scale
Find fourth proportional to 162.41, 243.30 and 145.50
Double scale
Find fourth proportional to 82.20, 123.15 and 73.75
Similar ratio
Find fourth proportional to 121.80, 182.48 and 109.12
1.5x scale
Why These Related Problems?
These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.