Table schema:
CREATE TABLE table_name_45 (height__m_ INTEGER, peak VARCHAR, class VARCHAR, prom__m_ VARCHAR)

Question: What is the average height for hewitt class, with prom less than 86, and a Peak of gragareth?
SQL: SELECT AVG(height__m_) FROM table_name_45 WHERE class = "hewitt" AND prom__m_ < 86 AND peak = "gragareth"