Home / 64.78-89.36-39.89

Finding the Fourth Proportional to 64.78, 89.36 and 39.89

Calculator

Solution

The fourth proportional to 64.78, 89.36 and 39.89 is: 55.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    64.78 : 89.36 = 39.89 : x
  2. Step 2: Convert to fraction form
    64.78/89.36 = 39.89/x
  3. Step 3: Cross multiply
    64.78x = 89.36 × 39.89
  4. Step 4: Simplify right side
    64.78x = 3,564.88
  5. Step 5: Solve for x
    x = 3,564.88/64.78
  6. Step 6: Final answer
    x = 55.03

Related Problems

Find fourth proportional to 32.39, 44.68 and 19.95
Half scale
Find fourth proportional to 129.56, 178.73 and 79.78
Double scale
Find fourth proportional to 65.78, 90.74 and 40.89
Similar ratio
Find fourth proportional to 97.17, 134.04 and 59.84
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.