Suppose 14 children, who were learning to ride two-wheel bikes, were surveyd to determine how long they had to use training whells. It was revealed that they used them an average of six months with a sample standard deviation of three months. Assume the underlying population distribution is normal.
When designing a study to determine this population proportion, what is the minimum number you would need to survey to be 90% confident that the population proportion is estimated within 0.05?