# Help with math questions **URL:** \ **Category:** Factual Questions\ **Created:** [May 26, 2017, 2:16am UTC](https://boards.straightdope.com/t/help-with-math-questions/787455 "2017-05-26T02:16:34Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Reddy\_Mercury](https://avatars.discourse-cdn.com/v4/letter/r/43a26b/32.png) [@Reddy\_Mercury](https://boards.straightdope.com/u/Reddy_Mercury)\ **Post date:** [May 26, 2017, 2:16am UTC](https://boards.straightdope.com/t/help-with-math-questions/787455/1 "2017-05-26T02:16:34Z")
I just want to check some questions I had on a test today, and see if I got the right answers. If anyone would help with the answers, that’d be great: 1. Ted took a standardized test. If 53% of the students scored below Ted, 4% had the same score and 43% had a higher score, what percentile was Ted in? 2. Assume a set of test scores is normally distributed with a mean of 545, and a standard deviation of 30. About what percentage of test scores lies between 515 and 545? 3. Suppose that in a company with 5000 employees, the monthly salaries are normally distributed. The mean salary is $3300, with a standard deviation of $600. About how many of the employees earn more than $3060 per month? 4. Assume a set of test scores is normally distributed with a mean of 70 and a standard deviation of 10. In what percentile is a score of 65? (I have the exact questions because the test was 24 questions drawn from a 100 question practice test, and I remember which questions I answered today). ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [May 26, 2017, 2:44am UTC](https://boards.straightdope.com/t/help-with-math-questions/787455/2 "2017-05-26T02:44:07Z")
What were your answers? ---
**Author:** ![Reddy\_Mercury](https://avatars.discourse-cdn.com/v4/letter/r/43a26b/32.png) [@Reddy\_Mercury](https://boards.straightdope.com/u/Reddy_Mercury)\ **Post date:** [May 26, 2017, 2:56am UTC](https://boards.straightdope.com/t/help-with-math-questions/787455/3 "2017-05-26T02:56:08Z")
1. 57% 2. 34% 3. 1723 4. 30th Percentile. ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [May 26, 2017, 2:57am UTC](https://boards.straightdope.com/t/help-with-math-questions/787455/4 "2017-05-26T02:57:40Z")
I’ll only address the first one in case it’s homework. In any case, this one will deepnd on eaxactly what definition you use. Some define percentile as percentage of scores in its frequency distribution that are equal to or lower than it. Others define percentile and the percent of scores lower plus half the tied scores. I don’t know how your instructor wants it defined. Were you paying attention? ---
**Author:** ![Reddy\_Mercury](https://avatars.discourse-cdn.com/v4/letter/r/43a26b/32.png) [@Reddy\_Mercury](https://boards.straightdope.com/u/Reddy_Mercury)\ **Post date:** [May 26, 2017, 3:02am UTC](https://boards.straightdope.com/t/help-with-math-questions/787455/5 "2017-05-26T03:02:03Z")
> [@OldGuy](#): > > I’ll only address the first one in case it’s homework. In any case, this one will deepnd on eaxactly what definition you use. Some define percentile as percentage of scores in its frequency distribution that are equal to or lower than it. Others define percentile and the percent of scores lower plus half the tied scores. I don’t know how your instructor wants it defined. Were you paying attention? The former I believe. My answer was 57% ---
**Author:** ![Oukile](https://avatars.discourse-cdn.com/v4/letter/o/13edae/32.png) [@Oukile](https://boards.straightdope.com/u/Oukile)\ **Post date:** [May 26, 2017, 4:49am UTC](https://boards.straightdope.com/t/help-with-math-questions/787455/6 "2017-05-26T04:49:00Z")
You got (3) wrong (you gave the number of employees with less than 3060). The rest looks good (although it may depend on the definition of percentile). They gave you a normal distribution table or calculator, right? ---
**Author:** ![Reddy\_Mercury](https://avatars.discourse-cdn.com/v4/letter/r/43a26b/32.png) [@Reddy\_Mercury](https://boards.straightdope.com/u/Reddy_Mercury)\ **Post date:** [May 26, 2017, 4:54am UTC](https://boards.straightdope.com/t/help-with-math-questions/787455/7 "2017-05-26T04:54:42Z")
> [@Oukile](#): > > You got (3) wrong (you gave the number of employees with less than 3060). The rest looks good (although it may depend on the definition of percentile). > > They gave you a normal distribution table or calculator, right? I had a calculator. But what do you mean depends on the meaning of percentile? ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [May 26, 2017, 4:57am UTC](https://boards.straightdope.com/t/help-with-math-questions/787455/8 "2017-05-26T04:57:57Z")
> [@Oukile](#): > > You got (3) wrong (you gave the number of employees with less than 3060). The rest looks good (although it may depend on the definition of percentile). > > They gave you a normal distribution table or calculator, right? Yeah, unless there’s a typo, (3) is definitely wrong, since the employees that earn more than $3060 per month would include all 2500 of them (50%) who earn more than the mean of $3300, as well as all the others who earn between $3060 and $3300. ---
**Author:** ![Oukile](https://avatars.discourse-cdn.com/v4/letter/o/13edae/32.png) [@Oukile](https://boards.straightdope.com/u/Oukile)\ **Post date:** [May 26, 2017, 4:47pm UTC](https://boards.straightdope.com/t/help-with-math-questions/787455/9 "2017-05-26T16:47:06Z")
> [@Reddy\_Mercury](#): > > I had a calculator. But what do you mean depends on the meaning of percentile? I meant the same thing than OldGuy ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [May 27, 2017, 1:00am UTC](https://boards.straightdope.com/t/help-with-math-questions/787455/10 "2017-05-27T01:00:25Z")
> [@engineer\_comp\_geek](#): > > What were your answers? Ah, the mods. Always on guard…