Home / 715.80-987.81-401.09

Finding the Fourth Proportional to 715.80, 987.81 and 401.09

Calculator

Solution

The fourth proportional to 715.80, 987.81 and 401.09 is: 553.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.80 : 987.81 = 401.09 : x
  2. Step 2: Convert to fraction form
    715.80/987.81 = 401.09/x
  3. Step 3: Cross multiply
    715.80x = 987.81 × 401.09
  4. Step 4: Simplify right side
    715.80x = 396,195.77
  5. Step 5: Solve for x
    x = 396,195.77/715.80
  6. Step 6: Final answer
    x = 553.50

Related Problems

Find fourth proportional to 357.90, 493.91 and 200.54
Half scale
Find fourth proportional to 1,431.60, 1,975.62 and 802.17
Double scale
Find fourth proportional to 716.80, 989.19 and 402.09
Similar ratio
Find fourth proportional to 1,073.70, 1,481.72 and 601.63
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.