select round(sum(LAT_N),4) from station where LAT_N < 137.2345 and LAT_N>38.7880;

SELECT CAST(ROUND(SUM(lat_n), 4, 1) AS DECIMAL(10,4)) FROM station WHERE lat_n > 38.7880 AND lat_n < 137.2345;

select cast(Round(sum(lat_n),4) as decimal(10,4)) from station where lat_n>38.7880 and lat_n <137.2345;

For MySQL Platform

Using BETWEEN operator will give you the same result. But as per question, its wrong to use that operator because when using BETWEEN, both the start(38.7880) and end(137.2345) are included. If you read the question carefully, its greater than 38.7880(not >=) and less than 137.2345(not <=)

In MySQL, There is a seperate function for truncating a decimal unlike standard ROUND function in other platforms. And that function is TRUNCATE

SELECT TRUNCATE(SUM(lat_n), 4) FROM station
WHERE lat_n > 38.7880 AND lat_n < 137.2345;

for ms sql server - SELECT CAST(FLOOR(SUM(LAT_N) * 10000) / 10000.0 AS DECIMAL(15,4)) FROM STATION WHERE LAT_N > 38.7880 AND LAT_N < 137.2345;