Lin ride her bike 20 miles in 15 minutes. If she rode at constant speed what is the unit rate and how do you know ?

1 answer:

6 0

$v=\frac{d}{t} \ \ \where: v=spped \ \ \ d=distane \ \ \ \ t=time\\
\\
\boxed{v=\frac{20 \ mi}{\frac{1}{4} \ h}=20*4=80 \ mi/h}$

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On a school trip to a theme park, 4 busses each carry 70 students.

DanielleElmas [232]

Answer:

165 Students Have No Made Plans For Lunch.

Step-by-step explanation:

According To the Question,

Given,On a school trip to a theme park, 4 busses each carry 70 students Then Total Number Of Students on a trip is 70×4=280 Students.

And,35% of the students are bringing their own lunch. Thus,35% Of 280 Students is 98 Students. Then Remaining 182 Students not bring their own lunch.

Now, 17 of the students are buying lunch when they get to the theme park. Thus students Who have not made plans for lunch is 182-17⇒165Students

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In a shipment of 56 vials, only 13 do not have hairline cracks. If you randomly select 3 vials from the shipment, in how many wa

Elden [556K]

Answer: 27434

Step-by-step explanation:

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The number of combinations of m thing r things at a time is given by :-

$^nC_r=\dfrac{n!}{r!(n-r)!}$

Now, the number of ways to select at least one out of 3 vials have a hairline crack will be :-

$^{13}C_2\cdot ^{43}C_{1}+^{13}C_{1}\cdot ^{43}C_{2}+^{13}C_0\cdot ^{43}C_{3}\\\\=\dfrac{13!}{2!(13-2)!}\cdot\dfrac{43!}{1!(42)!}+\dfrac{13!}{1!(12)!}\cdot\dfrac{43!}{2!(41)!}+\dfrac{13!}{0!(13)!}\cdot\dfrac{43!}{3!(40)!}\\\\=\dfrac{13\times12\times11!}{2\times11!}\cdot (43)+(13)\cdot\dfrac{43\times42\times41!}{2\times41!}+(1)\dfrac{43\times42\times41\times40!}{6\times40!}\\\\=3354+11739+12341=27434$