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17 Oct 2019, 22:12
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D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
85%
(hard)
Question Stats:
55% (03:05) correct
45%
(03:16)
wrong
based on 230
sessions
History
Date
Time
Result
Not Attempted Yet
A biotechnologist started automated half-hourly recording of the conditions of a cell culture at 9 AM on 13 January, 2015. The dial on the recording device moved clockwise through one interval (for example, from A to B) after every 10 recordings. If the dial was at point A at 9 AM on 13 January, 2015, what was the position of the dial, time and date respectively when the 420th recording of the cell culture was taken?
A. B, 3 AM, 21 January, 2015
B. B, 6 AM, 21 January, 2015
C. C, 6 PM, 21 January, 2015
D. C, 3 AM, 22 January, 2015
E. B, 6 AM, 22 January, 2015
A. B, 3 AM, 21 January, 2015
B. B, 6 AM, 21 January, 2015
C. C, 6 PM, 21 January, 2015
D. C, 3 AM, 22 January, 2015
E. B, 6 AM, 22 January, 2015
Attachments
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18 Oct 2019, 12:10
Kudos
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the given says that : 0.5 hour ≡ 1 recording , and 10 recordings ≡ 1 interval,
so we can deduce that 10 recordings ≡ 1 interval ≡ 5 hours
then 420 recordings ≡ 42 intervals ≡ 210 hours
the dial has 10 letters, so after each 10 intervals, it will return to its initial position A,
then after 42 intervals, it will be on C --> Eliminate (A,B,E)
210 hours represents 8 days and 18 hours,
so 9 am + 18 hours = 24 hours + 3am --> Eliminate (C)
and 13 January + 8 days + 24 hours = 22 January --> D
so we can deduce that 10 recordings ≡ 1 interval ≡ 5 hours
then 420 recordings ≡ 42 intervals ≡ 210 hours
the dial has 10 letters, so after each 10 intervals, it will return to its initial position A,
then after 42 intervals, it will be on C --> Eliminate (A,B,E)
210 hours represents 8 days and 18 hours,
so 9 am + 18 hours = 24 hours + 3am --> Eliminate (C)
and 13 January + 8 days + 24 hours = 22 January --> D
01 Jan 2021, 05:31
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Kinshook
Solution:
Since 420 recordings were taken and since recordings are taken every 30 minutes, the 420th reading is taken 210 hours after 9 AM on January 13th. Notice that 210 hours = 8 days 18 hours. Notice also that 8 days from 9 AM, January 13th is 9 AM, January 21st. Adding another 18 hours, we arrive at 3 AM, January 22nd. There is only one answer choice with this date and time, so the correct answer is D.
Answer: D
