A three hours' journey a four weeks' course

[Anna232]

As "three hours' journey" and "four weeks' English course" are wrong while "a three-hour journey" and "a four-week English course are right. I am trying to find out why in some cases 's or a - are both correct (a five-minute walk, five minutes' walk) but in some cases only the hypen is used ("a three-hour journey" and "a four-week English course). Does it depend on each word? Is there a particular rule?

 

[Tarheel]

I do know that we usually use the singular with the adjective.

 

[emsr2d2]

As "three hours' journey" and "four weeks' English course" are wrong while "a three-hour journey" and "a four-week English course are right. I am trying to find out why in some cases 's or a - are both correct (a five-minute walk, five minutes' walk) but in some cases only the hypen is used ("a three-hour journey" and "a four-week English course). Does it depend on each word? Is there a particular rule?

I'm sure someone will come along and prove me wrong, but I would say that we use "[no article] number, apostrophe, s" only with periods of time together with certain methods of travel.

It's a one-minute bike ride.
It's one minutes' bike ride.
It's a twenty-minute jog from there.
It's twenty minutes' jog from there.
It's a five-minute walk.
It's five minutes' walk.
It's a four-hour drive from here.
It's four hours' drive from here.

It's a ten-year plan.
It's ten years' plan.
It's a three-hour journey.
It's three hours' journey.
It's a twelve-week French course.
It's twelve weeks' French course.

 

[Anna232]

I'm sure someone will come along and prove me wrong, but I would say that we use "[no article] number, apostrophe, s" only with periods of time together with certain methods of travel.

It's a one-minute bike ride.
It's one minutes' bike ride.
It's a twenty-minute jog from there.
It's twenty minutes' jog from there.
It's a five-minute walk.
It's five minutes' walk.
It's a four-hour drive from here.
It's four hours' drive from here.

It's a ten-year plan.
It's ten years' plan.
It's a three-hour journey.
It's three hours' journey.
It's a twelve-week French course.
It's twelve weeks' French course.

Thank you so much. That's exactly what I was trying to find out. But when both are used, there is no difference in meaning, is there? For example, a two-week holiday and two weeks' holiday, mean the same, don't they?

 

[emsr2d2]

Thank you so much. That's exactly what I was trying to find out no full stop here but when both are used, there is no difference in meaning, is there? For example, "a two-week holiday" and "two weeks' holiday" no comma here mean the same, don't they?

Note my changes above. I always discourage learners from trying to start sentences with "But". It can be done but it's usually better to use it as a conjunction.
I've crossed out "when both are used". That suggests that you want to use the two phrases together in one sentence. That wouldn't make sense. You would use one or the other.
Remember to mark out words/phrases you're asking us to consider in some way. I've put them in quotation marks above.
Whenever you ask us if two things mean the same, give us complete sentences to consider.

 

[Anna232]

Note my changes above. I always discourage learners from trying to start sentences with "But". It can be done but it's usually better to use it as a conjunction.
I've crossed out "when both are used". That suggests that you want to use the two phrases together in one sentence. That wouldn't make sense. You would use one or the other.
Remember to mark out words/phrases you're asking us to consider in some way. I've put them in quotation marks above.
Whenever you ask us if two things mean the same, give us complete sentences to consider.

I mean if I use either, isn't the meaning the same?
1. I am going to have two weeks' holiday.
2. I am going to have a two-week holiday.

 

[Tarheel]

Those mean the same thing.

Perhaps:

Doesn't it mean the same thing whichever one I use?

 

[emsr2d2]

I mean if I use either, isn't the meaning the same?

1. I am going to have two weeks' holiday.
2. I am going to have a two-week holiday.

If you mean you're going on holiday (going away from home) for a period of two weeks, I wouldn't use #1. That's the kind of thing you might say to express that you're going to have two weeks' off from work.
As suggested by my opening sentence, the most natural way of saying it is "I'm going on holiday for two weeks".