CAPE Applied Mathematics Unit 1 · 2016 · Paper 1 · Question Q43

The weights of iron rods manufactured by a certain company are normally distributed with a standard deviation of 3.4\text{ kg}. A random sample of 35 iron rods with mean weight of 40.2\text{ kg} is selected. A 99% confidence interval for the population mean is

1. (A)(38.7, 41.7)\text{ kg}
2. (B)(38.9, 41.5)\text{ kg}
3. (C)(41.5, 38.9)\text{ kg}
4. (D)(41.7, 38.7)\text{ kg}