Logical error in query formation without using DISTINCT in query in mysql

Question

Find the makers of the PCs that have speed not less than 450MHz. Result set: Maker.

My Query -

SELECT maker FROM product
WHERE model IN ( SELECT model FROM pc WHERE speed > 450 ) AND type = 'PC'

Output -

however i tried by adding DISTINCT in my query and its giving the desired output, but there is some logical error in my query as it is not passing the system.

DB Schema -

SELECT * FROM product --

SELECT * FROM pc  --

Answer 1

you can use JOIN

SELECT  DISTINCT b.maker
FROM    PC a
        INNER JOIN Product b
           ON a.model = b.model
WHERE   speed >= 450

Answer 2

Or simply this too works,

Select distinct Product.maker from Product, PC
where Product.model = PC.model
and PC.speed >= 450