To comply with laws regarding the use of personally identifiable infor

Question

To comply with laws regarding the use of personally identifiable information, a certain company must adopt a new way of determining its customer identification numbers (CIDs) in its customer records database. Proposals are being considered on the basis of the following principles:

• Database Constraints: Each character in each CID must be from the following table:

• Error Checking: There must be some mechanism for determining if a CID could be valid without checking the database.

• Meaningful: Each CD must reflect some information about the customer to which it is assigned.

Whichever proposal is adopted, the new CIDs will be issued to all former customers currently in the database.

chetan2u · Accepted Answer

1. Suppose that Proposal 2 has been adopted and that a customer has been issued a CID of 1039str0129016. For each of the following statements about this customer, select Could be true if, in light of the given information, the statement could be true. Otherwise, select Could not be true.

- 4 random numbers: 1039
- First 3 alphanumber allowablecharacters of email str
- hhmmss of the 1st purchase: 01:29:01
- Checking digit: 6

The customer's email was [email protected]. => Could not be true
str must be reversely transformed to another 3 characters

The customer began shopping at 10:39 in the evening on the day before the first purchase. => Could be true
The customer could start shopping at 10:39 p.m and ended up making the first purchase after a few hours, which is 1:29 a.m of the following day

The customer's first purchase was made 16 seconds after 1:29:00 in the morning. => Could not be true
The first purchase is made at 1:29:01, not 1:29:16

2. For each of the following principles named in the Customer Identifiers tab, select Explicitly mentioned in Proposal I if that principle is explicitly mentioned in the description of Proposal 1. Otherwise, select Not explicitly mentioned in Proposal 1.

Database Constraints => Explicitly
Only containing characters from the allowed table

Error Checking => Not Explicitly
This is only available in Proposal 2 (checking digit)

Meaningful => Explicitly
Having info of part of the email address and the time of 1st purchase

3. How many 3-character alphanumeric sequences can appear as the 5th, 6th, and 7th characters of a valid CID under Proposal 2? [32,768]

5th, 6th and 7th characters are those alphanumeric allowable characters (taken from the email address)

For Proposal 1: There are 36 (=6*6) allowable characters

For Proposal 2: There are only 32 left (= 36 - 4 letters a i o u which all become e)

Number of valid sequences: 32 * 32 * 32

- Method 1: Use the calculator
- Method 2:
+ Answer ends with 8 (=2*2*2)
+ Answer > 30 * 30 * 30 = 27,000
==> The only which fits is 32,768

laurynccc · Answer

3rd question solution.

The below is my calculation:

First, without any conditions, each possible value of 5th, 6th, and 7th could be 26 (alphabets) + 10 (numbers) =36 characters.
However, from the transformation form on the third tab, we must minus   from the possible characters, since they are all transformed to  .

We can finally get that 26-4 (alphabets) + 10 (numbers) = 32 (characters).
Since there's no limitation of redundancy, we can calculate it as 32*32*32=32,768.

diya7 · Answer

why do we do 32 raise to 3 ?

chetan2u · Answer

Hi

There are 3 places to be filled up, and each place can be filled up with any of the 32 possible alphanumeric values.

AnkurGMAT20 · Answer

chetan2u   KarishmaB  I didn't understand the explanation of question 3rd at all. Could you please help explaining it again?

chetan2u · Answer

The 14 alpha numerical code is ABCDEFGHIJKLMN 
The first four ABCD are randomly generated. 
8 to 13 are timings of purchase and the 14 is the unit digit of all numerical values.

We are concerned with 5, 6 and 7 place. 
These are taken from the mail and could be a digit or an alphabet. 
Proposal 1 does not put any restriction but proposal omits FOUR alphabets, so we can have anything other than these 4 alphabets. 
Thus, (26-4)+10 or 32 values. 
Each of 5th, 6th and 7th places can take any of the possible 32 values=> 32*32*32

Gemmie · Answer

1. Suppose that Proposal 2 has been adopted and that a customer has been issued a CID of 1039str0129016. For each of the following statements about this customer, select Could be true if, in light of the given information, the statement could be true. Otherwise, select Could not be true.

- 4 random numbers: 1039
- First 3 alphanumber allowablecharacters of email str
- hhmmss of the 1st purchase: 01:29:01
- Checking digit: 6

The customer's email was [email protected]. => Could not be true
str must be reversely transformed to another 3 characters

The customer began shopping at 10:39 in the evening on the day before the first purchase. => Could be true
The customer could start shopping at 10:39 p.m and ended up making the first purchase after a few hours, which is 1:29 a.m of the following day

The customer's first purchase was made 16 seconds after 1:29:00 in the morning. => Could not be true
The first purchase is made at 1:29:01, not 1:29:16

2. For each of the following principles named in the Customer Identifiers tab, select Explicitly mentioned in Proposal I if that principle is explicitly mentioned in the description of Proposal 1. Otherwise, select Not explicitly mentioned in Proposal 1.

Database Constraints => Explicitly
Only containing characters from the allowed table

Error Checking => Not Explicitly
This is only available in Proposal 2 (checking digit)

Meaningful => Explicitly
Having info of part of the email address and the time of 1st purchase

3. How many 3-character alphanumeric sequences can appear as the 5th, 6th, and 7th characters of a valid CID under Proposal 2? [32,768]

5th, 6th and 7th characters are those alphanumeric allowable characters (taken from the email address)

For Proposal 1: There are 36 (=6*6) allowable characters

For Proposal 2: There are only 32 left (= 36 - 4 letters a i o u which all become e)

Number of valid sequences: 32 * 32 * 32

- Method 1: Use the calculator
- Method 2:
+ Answer ends with 8 (=2*2*2)
+ Answer > 30 * 30 * 30 = 27,000
==> The only which fits is 32,768

sarthak1701 · Answer

3rd question solution.

We have 26 alphabets and digits that we can use to fill in the 5th, 6th, and 7th spaces in the CID, therefore we have 36 characters to choose from for each of the 3 spaces (repetitions allowed)

Normally, this would mean that we have 36^3 combinations but Proposal 2 has a restriction under which we can't use 4 letters and instead we have to use the letter 'e' in place of that, this reduces our characters to 32 but the formula remains the same.

We have 32 * 32 * 32 combinations. You could use the calculator here but it is quicker to estimate, 2^5 * 2^5 * 32= 2^10 * 32, 2^10 is 1024, so the answer should be 32 thousand something.

KK12333 · Answer

How did it began shopping at 10:39 if the numbers are randomly generated?  Bunuel   KarishmaB

cheshire · Answer

The time they begin shopping is a trap in this instance as it isn't relevant for the CID, the time they made their first purchase is relevant however. As long as those two pieces of information do not conflict, the first doesn't matter. The fact that the time they started shopping and the randomly generated digits are the same is a coincidence meant to confuse you.

SukhAgam · Answer

hi chetanu2u, I a not able to understand as in proposal 1 it is explicitly mentioned that timestamp would there after 3 alphabets in cid after it timestamp will be followed but in proposal 2 it is saying that it is an extension of proposal 1 and character will be transformed according to the table but in that too 5,6 and 7 place are filled by numbers so how can we say that these places can be filled with alphabets shouldn't it be filled with numbers only from 0-9....Kindly help me with this....

Bunuel · Answer

The 5th, 6th, and 7th characters come from the first three characters of the customer’s email in Proposal 1, not from the timestamp. Since they’re from the email, they can be letters or digits, not just numbers.

lawyeroffduty · Answer

i still doesn't understand this part, can you please explain me again and if possible in detail with the proposal set mentioned in the question stem

Bunuel · Answer

In CID    1039  str  012901  6   :

• 1039 are random digits with no link to time, date, or any customer detail.

• str012901 comes from Proposal 1 after applying the transformation table to str. 012901 represents the timestamp of the first purchase at 1:29:01 AM.

• 6 is the check digit. To find it, add all numeric digits before it: 1 + 0 + 3 + 9 + 0 + 1 + 2 + 9 + 0 + 1 = 26, and the units digit of 26 is 6, which becomes the check digit.

Siddharth17 · Answer

there are 32 possible values - 0 to 9, then a through z except a, I, o, and U. so total 32 which can be chosen to fill the 3 spots. 32*32*32

	1,000
	10,648
	17,576
	32,768
	46,656

To comply with laws regarding the use of personally identifiable infor

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Could be true	Could not be true
		The customer's email was [email protected].
		The customer began shopping at 10:39 in the evening on the day before the first purchase.
		The customer's first purchase was made 16 seconds after 1:29:00 in the morning.

Explicitly mentioned in Proposal 1	Not explicitly mentioned in Proposal 1
		Database Constraints
		Error Checking
		Meaningful

GMAT Multi-Source Reasoning (MSR) Questions

To comply with laws regarding the use of personally identifiable infor

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