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How many multiples of 7 are there between 21 and 343, exclusive ? A.
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21 Jun 2022, 01:38
21 Jun 2022, 01:38
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Question Stats:
55% (00:44) correct
44% (01:34) wrong based on 9 sessions
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How many multiples of 7 are there between 21 and 343, exclusive ?
A. 48
B. 47
C. 46
D. 45
E. 44
A. 48
B. 47
C. 46
D. 45
E. 44
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Re: How many multiples of 7 are there between 21 and 343, exclusive ? A.
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21 Jun 2022, 05:58
21 Jun 2022, 05:58
1
Carcass wrote:
How many multiples of 7 are there between 21 and 343, exclusive ?
A. 48
B. 47
C. 46
D. 45
E. 44
A. 48
B. 47
C. 46
D. 45
E. 44
ASIDE: there are various formulas that students can memorize for this kind of question. Here's a solution that uses a nice easy rule (which can be applied in many ways):
The number of integers from x to y inclusive equals y - x + 1
exclusive: so, we're not going to count 21 and 343
The multiples of 7 to be counted are:
28
35
42
.
.
.
336
We can REWRITE the values as follows:
28 = (7)(4)
35 = (7)(5)
42 = (7)(6)
.
.
.
336 = (7)(48)
So, we need only find the number of integers from 4 to 48 inclusive
Applying the above rule, the number of integers = 48 - 4 + 1 = 45
Answer: D
Cheers,
Brent
gmatclubot
Re: How many multiples of 7 are there between 21 and 343, exclusive ? A. [#permalink]
21 Jun 2022, 05:58
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