Is the number of seconds required to travel d1 feet at r1

I think it is combined together suff.

T1=D1/R1
T2=D2/R2

1. D1=D2+30 we cannot say anything using this info
2. R1=R2+30 the same not suff alone

now combine it:

T1=(D2+30)/(R2+30)
T2=D2/R2
from here i think only way to go with is plugging numbers. it should come with the answer then.

This last step is the problem exactly. I am not agreeing with the OA here.

What answer do you get?

i think combined 1 and 2 is suff. so C
there is no need for solving it further i guess. just plug any number D2 and R2 but i am not sure about the speed in seconds. i think distance will be longer so 100 then rate per second is small so 5 may be. then answer should come. T2>T1
not sure still
lets see what guys say. i would pick C

Well, neither of the statements is SUFF.

Taking both statements together.

T2 = (d2/r2)
T1 = (d1/r1) = (d2+30)/(r2+30)

Now,

Let's take two cases:

Case1: When d2 > r2

d2 = 100 and r2 = 10

In this case,
T2 = 10
T1 = 13/4 = 3.25

So T2 > T1

Case1: When d2 < r2

d2 = 100 and r2 = 200

In this case,
T2 = 1.5
T1 = 13/23 ~ 1.6

So T1 > T2

Hence both ST1 and ST2 are not sufficient.

I would go with E.

- Brajesh

I get E as well..

if D2=R2, then T1=T2

is D2 is different from R2 we will get a different answer...

E it is..

Plug in approach will work.

1. Take two cases. (i) d1=10 and d2 =40 and (ii) d1=110 and d2=140

(i) alone is not sufficient

2.Take two cases (i) r1=10, r2=40 (ii) r1=110 and r2=140

(ii) alone is not sufficient

3. Combine (i) and (ii). Take the extremes (i) d1=10 and r1=110 and d1=110 and r1=10 and (ii) d2=40 and r2=140 and d2=140 and r2=40

The different cases do not totally agree with one another.

So the answer is E.
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Is the number of seconds required to travel d1 feet at r1 feet per second greater than the number of seconds required to travel d2 feet at r2 feet per second?

We need to find whether \(\frac{d_1}{r_1}>\frac{d_2}{r_2}\).

(1) d1 is 30 greater than d2 --> \(d_1=d_2+30\). Nothing about the rates. Not sufficient.
(2) r1 is 30 greater than r2 --> \(r_1=r_2+30\). Nothing about the distances. Not sufficient.

(1)+(2) The question becomes whether \(\frac{d_2+30}{r_2+30}>\frac{d_2}{r_2}\). Now, if \(d_2=r_2\), then \(\frac{d_2+30}{r_2+30}=\frac{d_2}{r_2}\), thus in this case the answer would be NO but if \(d_2=1\) and \(r_2=2\), then in this case \(\frac{d_2+30}{r_2+30}=\frac{31}{32}>\frac{1}{2}=\frac{d_2}{r_2}\), thus in this case the answer would be YES. Not sufficient.

Answer: E.

OPEN DISCUSSION OF THIS QUESTION IS HERE: is-the-number-of-seconds-required-to-travel-d1-feet-at-r1-143694.html
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