<Tr> <Td> </Td> <Td> 23, 22, 21, 19, 18 </Td> </Tr> <Tr> <Td> 5 </Td> <Td> 21, 20, 19, 18, 17 </Td> </Tr> <P> The number of trials, mean, variance and standard deviation are presented in the next table . </P> <Table> <Tr> <Th> x </Th> <Th> n </Th> <Th> y </Th> <Th> s </Th> <Th> s </Th> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> 30.0 </Td> <Td> 1.0 </Td> <Td> 1.0 </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> 40.5 </Td> <Td> 1.67 </Td> <Td> 1.29 </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> 29.5 </Td> <Td> 4.5 </Td> <Td> 2.12 </Td> </Tr> <Tr> <Td> </Td> <Td> 5 </Td> <Td> 20.6 </Td> <Td> 4.3 </Td> <Td> 2.07 </Td> </Tr> <Tr> <Td> 5 </Td> <Td> 5 </Td> <Td> 19.0 </Td> <Td> 2.5 </Td> <Td> 1.58 </Td> </Tr> </Table>

When do you pool the standard error of proportion estimates