还是英文的统计学问题weekly demand at a grocery store for a brand of breakfast cereal is normally distributed with a mean of 800 boxes and a standard deviation of 75 boxes.a) what is the probability that weekly demand is more than 959 boxes?

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还是英文的统计学问题weeklydemandatagrocerystoreforabrandofbreakfastcerealisnormallydistributedwithameanof800bo

还是英文的统计学问题weekly demand at a grocery store for a brand of breakfast cereal is normally distributed with a mean of 800 boxes and a standard deviation of 75 boxes.a) what is the probability that weekly demand is more than 959 boxes?
还是英文的统计学问题
weekly demand at a grocery store for a brand of breakfast cereal is normally distributed with a mean of 800 boxes and a standard deviation of 75 boxes.
a) what is the probability that weekly demand is more than 959 boxes?
b) what is the probability that weekly demand is between 650 boxes and 950 boxes?
c) the store orders cereal from a distributor weekly.how many minimun of boxes should the store order for a week to have at most a 1% chance of running short of this brand of cereal during the week?
d).what is the probability that a segment of 6 brands in the grocery store have a weekly mean demand that is greater than 900 boxes?
我是在问统计学 不是翻译

还是英文的统计学问题weekly demand at a grocery store for a brand of breakfast cereal is normally distributed with a mean of 800 boxes and a standard deviation of 75 boxes.a) what is the probability that weekly demand is more than 959 boxes?
1)用950-800=150,再用150除于标准差75,得到2,查正态分布表得临界值2对应的概率大约为5%,所以提供950份以上的概率是5%
2)800-650=150,因为正态分布是对称的,所以提供650份以下的概率是5%,650份到950份之间的概率为90%
3)查正态分布表,得出1%时的临界值,用其乘以标准差得出一个数,再用800减去这个数就是结果
4)应该是一个联合分布的问题吧,题意理解不清,sorry.

我不知道标准偏差是什么意思
每周平均订餐800份,标准差为75份;
1)需要提供950分的概率;
2)提供650份至950份的概率;
3)按发生概率1%计算,这个店最少的订餐份数是多少;
4)订餐份数超过900份的概率。