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How many threedigit numerals begin With a digit that represents a pri
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12 Nov 2018, 10:26
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How many threedigit numerals begin With a digit that represents a prime number and end with a digit that represents a prime number? (A) 16 (B) 80 (C) 160 (D) 180 (E) 240 Project PS Butler : Question #14 Subscribe to get Daily Email  Click Here  Subscribe via RSS  RSS
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Re: How many threedigit numerals begin With a digit that represents a pri
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12 Nov 2018, 10:41
Let number be X X X. First and last spots can be taken by 2, 3, 5, 7, so 4 numbers for each spot. Middle spot can be taken by any of the 10 digits. So, my guess is 4*10*4 = 160 is the answer. Option C
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Re: How many threedigit numerals begin With a digit that represents a pri
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13 Nov 2018, 02:22
HKD1710 wrote: How many threedigit numerals begin With a digit that represents a prime number and end with a digit that represents a prime number? (A) 16 (B) 80 (C) 160 (D) 180 (E) 240 Project PS Butler : Question #14 Subscribe to get Daily Email  Click Here  Subscribe via RSS  RSSThe Fundamental Counting Principle (also called the counting rule) is a way to figure out the number of outcomes in a probability problem. Basically, you multiply the events together to get the total number of outcomes. The formula is: If you have an event “a” and another event “b” then all the different outcomes for the events is a * b. "AND" means multiplication Source: https://www.statisticshowto.datascience ... principle/ So, Stage 1. 4 numbers ( 2, 3, 5, 7) Stage 2. 10 numbers ( 0, 1, 2, 3, 4, 5, 6, 7, 8, 9) Stage 3. 4 numbers (2, 3, 5, 7) Stage 4. Kill that annoying fly that is buzzing around your office \(4*10*4 = 160\) pushpitkc, how are you there ? i have one question to clear my confusions when do i need to use slot method ? i also was thinking like this: 4 numbers in 4! ways 10 numbers in 10! ways 4 numbers in 4! ways! 4!*10!*4!



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Re: How many threedigit numerals begin With a digit that represents a pri
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13 Nov 2018, 05:09
dave13 if I may chip in my two cents, You have to use factorial to list out the possibke permutations in an order. Here you are just selecting numbers ( digits of a three digit number with constraints) So your answer is almost correct albeit the factorial sign. 4 ways to choose a prime. The three digit number will begin and end with a prime and the middle digit will have 10 options. Hence, 4*10*4 = 160 Does this make sense? Best, Gladi
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Re: How many threedigit numerals begin With a digit that represents a pri
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24 Nov 2018, 03:57
Gladiator59 wrote: dave13 if I may chip in my two cents, You have to use factorial to list out the possibke permutations in an order. Here you are just selecting numbers ( digits of a three digit number with constraints) So your answer is almost correct albeit the factorial sign. 4 ways to choose a prime. The three digit number will begin and end with a prime and the middle digit will have 10 options. Hence, 4*10*4 = 160 Does this make sense? Best, Gladi No ways to select the first no is 4 no of ways to select middle no is 10 Why is the no ways to select the third no is 4 and not 3? If we select 4, are not we repeating same combination? Please clarify.
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Re: How many threedigit numerals begin With a digit that represents a pri
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08 Jun 2019, 03:50
aghosh54 wrote: Gladiator59 wrote: dave13 if I may chip in my two cents, You have to use factorial to list out the possibke permutations in an order. Here you are just selecting numbers ( digits of a three digit number with constraints) So your answer is almost correct albeit the factorial sign. 4 ways to choose a prime. The three digit number will begin and end with a prime and the middle digit will have 10 options. Hence, 4*10*4 = 160 Does this make sense? Best, Gladi No ways to select the first no is 4 no of ways to select middle no is 10 Why is the no ways to select the third no is 4 and not 3? If we select 4, are not we repeating same combination?Please clarify. yes we are repeating it, but thats okay, according to the condition... Start with a prime digit, and end with a prime digit, doesn't say, "it can't have repeating prime digits" then, the answer will be 4*10*3 = 120 I guess so here the answer is fine, 4*10*4 = 160.




Re: How many threedigit numerals begin With a digit that represents a pri
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08 Jun 2019, 03:50






