A university warehouse has received a shipment of 25 printers, of which 10 are laser printers and 15 are inkjet models. If 8 of these 25 are selected at random to be checked by a particular technician then find mean and variance for the laser printers?
Answers
Answered by
0
Explanation:
Laser Printer = 10
Inkjet Printers = 15
Total Printers = 25
6 Printers can be selected in ²⁵C₆
3 to be exactly laser printers ¹⁰C₃ * ¹⁵C₃
Probability of exactly 3 laser printers = ¹⁰C₃ * ¹⁵C₃ / ²⁵C₆
¹⁰C₃ = 10 * 9 * 8/ (3 * 2 * 1)= 120
¹⁵C₃ = 455
²⁵C₆ = 177100
P = 120 *455 / 177100 = 0.308
at least 3 inkjet printers are selected
3 inkjet + 4 inkjet + 5 inkjet + 6 inkjet
= (¹⁵C₃* ¹⁰C₃ + ¹⁵C₄* ¹⁰C₂ + ¹⁵C₅* ¹⁰C₁ + ¹⁵C₆* ¹⁰C₀)
= (455*120 + 1365*45 + 3003*10 + 5005*1)
= 54600 + 61425 + 30030 + 5005
= 151060
Probability = 151060/177100 = 0.853
Please mark me as brainliest
Similar questions