Question: In Numbers 4:3 it says that the sons of Levi who were to serve in the Tabernacle were from 30 years old to 50; but in 8:24, it states the age is from 25 to 50. Please explain this contradiction.
Answer: The tribe of Levi was given the responsibility of setting up and taking down the Tabernacle, itself, and all the articles within the Tabernacle. For example, the Ark of the Covenant, the mercy seat, the table of shewbread, the laver, the menorah, the altar of incense, brazen altar, and other things all had to be set up and taken down every time the Tabernacle was moved.
In Numbers 4:3, the age of the men was specifically fixed at 30 as being of full maturity to perform the laborious duties, as well as the mental acuity required to assist in the management of the sacred services.
Numbers 8:24, which states that the age to start their services at 25; seems to contradict 4:3, which states the age as 30. As one studies the Rabbinical writings and Jewish History, we find that they entered into their work or responsibilities in their 25th year.
For 5 years they were in their apprenticeship, until the age of 30. During their apprenticeship they were occasionally allowed to do the services; but, at the age of 30, they were in full-time service until the age of 50.
There is no contradiction at all. From age 25 to 30 they were being trained as pupils and probationers, under the guidance and direction of their senior brothers. At 30, they were admitted to the full discharge of their official duties.