เราเรียนพยายามอ่านแล้วลองทำโจทย์ 2 ข้อนี้ แต่ไม่เข้าใจเลยค่ะ รบกวนเพื่อนๆพี่อธิบายเป็นขั้นตอนให้เข้าใจด้วยนะคะ ออกตัวก่อนไม่ใช่การบ้านนะคะแหะๆ ลองทำข้อสอบเก่าดูค่ะ แต่ ทำไม่ได้
1 A local supermarket receives daily product delivery each morning at a time that varies uniformly between 6:00am and 8:00am. What delivery time can you be confident in stating that 95 percent of deliveries will arrive before?
2 The maintenance department of a city’s electric power company finds that it is cost-efficient to replace all street-light bulbs at once, rather than to replace the bulbs individually as they burn out. Assume that the lifetime of a bulb is normally (Gaussian) distributed with a mean of 8000 hours and a standard deviation of 300 hours. If the department wants no more than 3% of the bulbs to burn out before they are replaced, after how many hours should all of the bulbs be replaced?
รบกวนอธิบาย statistic ข้อนี้ให้ฟังหน่อยค่ะ
1 A local supermarket receives daily product delivery each morning at a time that varies uniformly between 6:00am and 8:00am. What delivery time can you be confident in stating that 95 percent of deliveries will arrive before?
2 The maintenance department of a city’s electric power company finds that it is cost-efficient to replace all street-light bulbs at once, rather than to replace the bulbs individually as they burn out. Assume that the lifetime of a bulb is normally (Gaussian) distributed with a mean of 8000 hours and a standard deviation of 300 hours. If the department wants no more than 3% of the bulbs to burn out before they are replaced, after how many hours should all of the bulbs be replaced?