Home / 75.21-112.80-21.09

Finding the Fourth Proportional to 75.21, 112.80 and 21.09

Calculator

Solution

The fourth proportional to 75.21, 112.80 and 21.09 is: 31.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    75.21 : 112.80 = 21.09 : x
  2. Step 2: Convert to fraction form
    75.21/112.80 = 21.09/x
  3. Step 3: Cross multiply
    75.21x = 112.80 × 21.09
  4. Step 4: Simplify right side
    75.21x = 2,379.45
  5. Step 5: Solve for x
    x = 2,379.45/75.21
  6. Step 6: Final answer
    x = 31.64

Related Problems

Find fourth proportional to 37.61, 56.40 and 10.55
Half scale
Find fourth proportional to 150.42, 225.61 and 42.19
Double scale
Find fourth proportional to 76.21, 114.30 and 22.09
Similar ratio
Find fourth proportional to 112.82, 169.21 and 31.64
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.