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Short-Term Actuarial Math Old Exam C Forum

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  #41  
Old 08-04-2018, 07:35 PM
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Hi,

Is there anyone using Coaching Actuaries bundle for this exam? Planning to take this next Feb and just want to get some feedback.
If someone from CA happens to read this, do you guys have any sample video?
Thanks.
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  #42  
Old 08-06-2018, 10:25 AM
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Originally Posted by avocado View Post
Hi,

Is there anyone using Coaching Actuaries bundle for this exam? Planning to take this next Feb and just want to get some feedback.
If someone from CA happens to read this, do you guys have any sample video?
Thanks.
Yes, we do. Go here and click on the Sample Video button. You can also go to the bottom of the page to get a free trial.
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  #43  
Old 08-07-2018, 01:35 AM
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Originally Posted by terencechow View Post
Yes, we do. Go here and click on the Sample Video button. You can also go to the bottom of the page to get a free trial.
Thanks, the trial is helpful!
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  #44  
Old 08-10-2018, 05:41 PM
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Originally Posted by avocado View Post
Planning to take this next Feb ...
Is it going to be offered then?
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  #45  
Old 08-10-2018, 07:07 PM
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I think I have more study material than I need.

I got the new ASM manual and ADAPT exam questions, just found out that the ASM manual also has access to online practice questions.

Has anyone here used the question bank from the ASM printed manuals? Same question bank right?

I've only had acess to ADAPT for 5 days and I think it might be too late to ask for a partial refund.
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  #46  
Old 08-10-2018, 08:00 PM
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Here's a question that I want to know how to calculate Var(Y) correctly using the inverse gamma if possible.


X follows a gamma distribution with parameters a=2.5 and theta=10

Y=(1/X)

evaluate Var(Y)


I did it and got 88.88888889 instead of .008888889
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  #47  
Old 08-10-2018, 09:08 PM
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When you transform a variable, you also have to transform the scale parameter. If X has scale parameter theta = 10, then 1/X has scale parameter 1/10. I suspect you are still using 10 instead of 1/10.

To see why, if X is Gamma with theta = 10, then X = 10 * W, where W is Gamma with theta = 1. 1/W is inverse Gamma with theta =1. But 1/X = 1/(10W) = (1/10) * 1/W, so 1/X is inverse Gamma with theta = (1/10) * 1 = 1/10.
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  #48  
Old 08-10-2018, 09:14 PM
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If X is Gamma with parameters alpha' and theta', then Y = 1 / X is Inverse Gamma with parameters alpha = alpha' and theta = 1 / theta'.

Here alpha' = 2.5 and theta' = 10 for the Gamma X, so alpha = 2.5 and theta = 1 / 10 = 0.1 for the Inverse Gamma Y.
From the tables, E[Y^2] = (0.1)^2 / [(2.5 - 1) (2.5 - 2)] = 0.04 / 3, while
E[Y] = (0.1) / (2.5 - 1) = 1 / 15.
Then Var[Y] = (0.04 / 3) - (1 / 15)^2 = 0.00888... .
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Last edited by Jim Daniel; 08-10-2018 at 09:15 PM.. Reason: Typo
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  #49  
Old 08-12-2018, 02:24 PM
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Quote:
Originally Posted by Jim Daniel View Post
If X is Gamma with parameters alpha' and theta', then Y = 1 / X is Inverse Gamma with parameters alpha = alpha' and theta = 1 / theta'.

Here alpha' = 2.5 and theta' = 10 for the Gamma X, so alpha = 2.5 and theta = 1 / 10 = 0.1 for the Inverse Gamma Y.
From the tables, E[Y^2] = (0.1)^2 / [(2.5 - 1) (2.5 - 2)] = 0.04 / 3, while
E[Y] = (0.1) / (2.5 - 1) = 1 / 15.
Then Var[Y] = (0.04 / 3) - (1 / 15)^2 = 0.00888... .
Quote:
Originally Posted by daaaave View Post
When you transform a variable, you also have to transform the scale parameter. If X has scale parameter theta = 10, then 1/X has scale parameter 1/10. I suspect you are still using 10 instead of 1/10.

To see why, if X is Gamma with theta = 10, then X = 10 * W, where W is Gamma with theta = 1. 1/W is inverse Gamma with theta =1. But 1/X = 1/(10W) = (1/10) * 1/W, so 1/X is inverse Gamma with theta = (1/10) * 1 = 1/10.
Thanks, that makes sense! Iíve redone this problem by correctly scaling my theta.
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  #50  
Old 08-15-2018, 05:39 PM
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I am going over some of the ASM problems for chain-ladder and I really feel like they missed some details. I calculated loss reserves on problem 7.7 in the manual and when I compare my solution to the book's I see that they subtract 1 from one of the development factors. I don't know why because the reading doesn't say this, I'm guessing because it wasn't developed to 12/31 of the final CY, because it does this again in chain ladder problems that don't give a date. It has me frustrated right now.

Last edited by A Pimp Named Slickback; 08-15-2018 at 05:44 PM..
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