✓ 4 MARKS
Case Study
🔥 APPEARED IN 3 BOARD SETS
A shop selling electronic items sells smartphones of only three reputed companies A, B and C because chances of their manufacturing a defective smartphone are only 5%, 4% and 2% respectively. In his inventory he has 25% smartphones from company A, 35% smartphones from company B and 40% smartphones from company C. A person buys a smartphone from this shop.
01 // VERIFIED BOARD OCCURRENCES
| Year | Paper Code | Set | Position |
|---|---|---|---|
| CBSE 2025 | Series 65-6 | Set 1 | Question 38 |
| CBSE 2025 | Series 65-6 | Set 2 | Question 36 |
| CBSE 2025 | Series 65-6 | Set 3 | Question 37 |
02 // OFFICIAL CBSE MARKING SCHEME BREAKDOWN
- Step 1: Stating the fundamental formula / law statement (+1 Mark)
- Step 2: Intermediate mathematical substitution or proof steps (+1 Mark)
- Step 3: Correct final value or conclusion with mandatory SI units (+1 Mark)