Home / 52.50-78.75-20

Finding the Fourth Proportional to 52.50, 78.75 and 20

Calculator

Solution

The fourth proportional to 52.50, 78.75 and 20 is: 30

Step by Step Solution

  1. Step 1: Write the proportion equation
    52.50 : 78.75 = 20 : x
  2. Step 2: Convert to fraction form
    52.50/78.75 = 20/x
  3. Step 3: Cross multiply
    52.50x = 78.75 × 20
  4. Step 4: Simplify right side
    52.50x = 1,575
  5. Step 5: Solve for x
    x = 1,575/52.50
  6. Step 6: Final answer
    x = 30

Related Problems

Find fourth proportional to 26.25, 39.38 and 10
Half scale
Find fourth proportional to 105, 157.50 and 40
Double scale
Find fourth proportional to 53.50, 80.25 and 21
Similar ratio
Find fourth proportional to 78.75, 118.13 and 30
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.