Can I run a 1:30 half marathon based on these times

Would be nice to know your mileage, but probably. You obviously have the leg speed but we don’t know anything about your endurance. Your 5k is pretty strong for a HS girl.

Easily. With a high mileage block (say 5-6 weeks up above 50 mpw and some 10+ mile long runs), you can run even faster. How much time after the season is over do you have before your race?

Surely you have enough information by now to work out what paces you should run for any each distance based on your race times and training?

Yes with those pr's you should be able to run 4:15 for 21k.

Yes 1:30 will be walk in the park for you.

Start at 1:30 pace for the first 10k then go for it if you feel good.

Based on 5k time I would put you near 1.25.

1.30 should be quite easy for you.

How can you run 4 miles at 6:00 but only 5k in 18:25?

Anyway with those mile and 2 mile times you should be aiming for something like 1:16.

With complete ease, yes.

18:25 5k is worth 23:56 4 miles.

Yes, 1:30 is definitely doable. I had 18:28/5K this spring and then 1:27/HM three weeks later ( I am M65). Was/am on 35-40 mpw, as you are. Lack of endurance became obvious after 15-16 km (10k split was near 41) but I had a good margin.

On a slightly slower mile and two mile than yours, but a faster 5k and 4 mile time (enroute in a 5), I did a 1:26 high. If your intention is to run a good half, then I recommend what my coach did, which was to improve times at an intermediate distance before moving up to a half. His line was sub 29 for 5 miles before racing a half. I think that’s your better goal for your development as a runner. Good luck.

Are you in HS? Your time would be better spent on getting that 5k time to match your mile time or getting ready to run faster than 4:50 indoors. You can run a 1:16-1:17 half off of a 4:50 &, with great endurance, take a crack at a sub-2:40 marathon. No point to chase that without building up your strength/endurance. Sub-1:30 should be a jog for you with a short specific block. Don't think there's any rush for you to get to that distance just to do it. Keep getting faster, balance out your PRs, debut at the half even faster than 1:16-1:17.

Can you? Certainly. 100%. Will you on your first try? I think there's a reasonable chance, but I wouldn't bet money on it (assuming from your reference to xc season that you're relatively young. Most youngsters underperform at longer distances; most oldsters underperform at shorter distances.)

You definitely have the speed to do it (quite easily), but your trajectory as you go up through the distances suggests you lack endurance.

As others have suggested, perhaps try to bump up your mileage a little, but don't go overboard. Pushing up to 45 mpw over the space of a month is enough.

You could also extend your long run out a few miles (2-3 extra).

I'd also suggest running some threshold intervals or continuous tempo runs. If you're unsure on the paces to run, going a little bit slower than threshold will give you a better stimulus than going too fast. Maybe try something like 3 x 10' @ goal HMP, with a 3 minute jog recovery.

You probably don’t realize it because your times and range indicate you’re relatively new to distance running, but once you are no longer crossing your lactate threshold you can hold a certain pace for a damn long amount of time seeing that you’re trained and fueled properly. It’s not the same thing as 400-800-mile-5k where you have a drop off in pace every time you move up in distance. The slowdown in race pace drop off happens for most 10k-10 miles, because this is where a lot of athletes will find their lactate threshold pace. If you sit right on your lactate threshold pace, you can maintain it for around 60 minutes if you are well rested and do enough training that your muscular system can hold up that long. A tad slower than that, we are talking 5-10 seconds a mile, and now you have your half marathon pace, and in VERY WELL trained athletes marathon pace is only 5-10 seconds per mile slower than that HM pace.

Im explaining this all to you because I don’t think you realize just how capable of not only 1:30 but maybe even 1:20 if you do the right training. If you can race 5:5x pace for 5k right now i’d bet money you are already in sub 1:30 shape, I think you should shoot for something like sub 1:25.

If you really wanna nail this half, i’d recommend getting 2-3 days a week of double digit miles, 10-14 of them, i’d lean to 10, even if they are just super easy miles. The only thing that will hurt you if trying to attempt a half somewhere in the 1:20s right now is that long distance endurance needed to keep your body together in those later miles. Breaking 1:30 shouldn’t even be aerobically challenging for you, it’s just a matter of if your body is ready to take that much of a beating. If your schedule doesn’t allow you to have a few double digit days a week, make sure you’re getting at least one.

Easily. My best 5k and 10k are 19:15 and 39:30. When I was in this kind of shape I've ran sub 1:30, out of 40 miles a week. Good luck.

OP didn’t ask if PRs were good. OP asked if they could break 90 min in a half marathon with those PRs. Unknown factors aside the answer is obviously yes. 4 miles in 6 flat pace indicates running 13.1 miles in 6:52 pace would be just fine for a goal. It’s up to OP to make it happen with the training/racing.

Based on your PRs, 1:30 should be a walk in the park, that's if you're aerobically trained enough, and have the endurance, to be comfortable with the 13.1 mile distance.

Maintain your 5K speed while getting your long run up to an hour and thirty minutes and you're there. Do some half marathon specific work and you're probably closer to 1:25. My two cents.