A consumer group is testing camp stoves. To test the heating capacity of a stove, it measures the time required to bring 2 quarts of water from 50 F to boiling. Two competing models are under consideration. Ten stoves of the first model and 12 stoves of the second model are tested. The following results are obtained:

| | Mean time | sigma | Sample size N |
|----:|----:|----:|----:|
| Model 1 | 11.4 min | 2.5 min | 10 |
| Model 2 | 9.9 min | 3.0 min | 12 |

Assume that time required to bring water to a boil is normally distributed for each stove. Compute the 95 % confidence interval for the difference of these two models of stoves.

```{r}

Required:

Insert R code below the line.