A psychologist hypothesizes that the children with type-K personality score higher than the children with type-R personality on an memory test. The estimated standard error turned out to be 0.9, while...

A psychologist hypothesizes that the children with type-K personality score higher than the children with type-R personality on an memory test. The estimated standard error turned out to be 0.9, while the mean score of type-K children was 18.8 and the mean score for type-R children was 21.3. What is the tscore?