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Speed bumps are being placed at 20 foot intervals along a ro
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23 Nov 2019, 19:26
23 Nov 2019, 19:26
00:00
Question Stats:
45% (00:48) correct
54% (01:03) wrong based on 11 sessions
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Speed bumps are being placed at 20 foot intervals along a road 1015 feet long. If the first speed bump is placed at one end of the road, how many speed bumps are needed?
(A) 49
(B) 50
(C) 51
(D) 52
(E) 53
(A) 49
(B) 50
(C) 51
(D) 52
(E) 53
Re: Speed bumps are being placed at 20 foot intervals along a ro
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23 Nov 2019, 19:27
23 Nov 2019, 19:27
huda wrote:
Speed bumps are being placed at 20 foot intervals along a road 1015 feet long. If the first speed bump is placed at one end of the road, how many speed bumps are needed?
(A) 49
(B) 50
(C) 51
(D) 52
(E) 53
(A) 49
(B) 50
(C) 51
(D) 52
(E) 53
why not 50?
Re: Speed bumps are being placed at 20 foot intervals along a ro
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24 Nov 2019, 09:09
24 Nov 2019, 09:09
Expert Reply
There’s a speed bump at one end of the road. If it’s at the beginning, then the speed bumps are at positions 20? feet for ?=0,1,…,50, with the last speed bump at 1000 feet. There are 51 integers in the set {0,1,2,…,50} so there are 51 speed bumps.
If it’s at the end of the road, there’s a speed bump at position 1015−20? feet for each ? from 0 through 50, and there are again 51 such values of ?.
If it’s at the end of the road, there’s a speed bump at position 1015−20? feet for each ? from 0 through 50, and there are again 51 such values of ?.
