如何用正态分布随机数来解决个R 的问题

我的问题如下：
一个超市连锁机构要对自家品牌的巧克力进行3个不同的促销方式。有18个店铺参与了促销方式。各抽六个做实验不同的促销方式。
要用正态分布随机来生成数据。后面要用到方差分析(Analysis of Variance，简称ANOVA)方法。但是我好想没有办法生成正确的3组数据。大家可以看看如何解决吗？
A supermarket chain decides to conduct an experiment to compare the sales effectiveness of three promotional scenarios for its home brand chocolate blocks:

1. Include home brand chocolate blocks in its weekly catalogue of specials
2. Promote home brand chocolate blocks with an end of isle display
3. Include home brand chocolate blocks in its weekly catalogue of specials, and at the same time promote the chocolate blocks with an end of isle display.
   Eighteen comparable stores in terms of sales and store size are selected for running this experiment over a given month. Each scenario is randomly allocated to six stores.
   a. Generate six monthly sales (recorded in thousands of units) for each scenario, according to the following:
   • All sales are normally distributed with a standard deviation of 10
   • Scenario 1 sales have a mean of 5
   • Scenario 2 sales have a mean of 6
   • Scenario 3 sales have a mean of 7.

问题相关代码

s1sales<-rnorm(6,mean=5,sd=10)
s2sales<-rnorm(6,mean=6,sd=10)
s3sales<-rnorm(6,mean=7,sd=10)

运行结果及报错内容

这个方法出来的3组数据，s1sales 有负数，s3sales 用shapiro.test 查了没有正态分布。
请教下这要从那个方面入手解决。谢谢。