In a stockpile of products produced by two machines M1 & M2, `40%` was manufactured by M1. `10%` of the products of M1 are defective & `95%` of products of M2 are not defective. What is the `%` of defective products in the stockpile?

Options

A. `14%`
B. `12%`
C. `7%`
D. `9%`

Answer

To find the percentage of defective products in the stockpile produced by machines M1 and M2, we can follow these steps:

### Step 1: Determine the total production
Assume the total production is 100 units. This makes calculations easier since we can directly use percentages.

### Step 2: Calculate the production from each machine
- Machine M1 produces 40% of the total production:
\[ \text{Production from M1} = 40\% \text{ of } 100 = 40 \text{ units} \]
- Machine M2 produces the remaining 60%:
\[ \text{Production from M2} = 60\% \text{ of } 100 = 60 \text{ units} \]

### Step 3: Calculate the number of defective products from M1
- 10% of the products from M1 are defective:
\[ \text{Defective from M1} = 10\% \text{ of } 40 = 4 \text{ units} \]

### Step 4: Calculate the number of defective products from M2
- 95% of the products from M2 are not defective, which means 5% are defective:
\[ \text{Defective from M2} = 5\% \text{ of } 60 = 3 \text{ units} \]

### Step 5: Calculate the total number of defective products
Now, we can find the total number of defective products from both machines:
\[ \text{Total defective products} = \text{Defective from M1} + \text{Defective from M2} = 4 + 3 = 7 \text{ units} \]

### Step 6: Calculate the percentage of defective products in the stockpile
Finally, to find the percentage of defective products in the entire stockpile:
\[ \text{Percentage of defective products} = \left( \frac{\text{Total defective products}}{\text{Total production}} \right) \times 100 = \left( \frac{7}{100} \right) \times 100 = 7\% \]

### Final Answer
The percentage of defective products in the stockpile is **7%**.

---