The time, t(in minutes), you need to type a certain paper varies inversely with the rate, r(in words per minute), that you can type. when typing 40 words per minute, you can finish in 50 minutes. find the constant of proportionality and write an equation relating t and r

Equation relating t and r  is and constant of proportionality  is 2000

Step-by-step explanation:

Given : the time, t(in minutes), you need to type a certain paper varies inversely with the rate, r(in words per minute), that you can type.

To Find: When typing 40 words per minute, you can finish in 50 minutes. find the constant of proportionality and write an equation relating t and r

Solution:

we are given that  t(in minutes), you need to type a certain paper varies inversely with the rate, r(in words per minute), that you can type.

So,

 ---1  Where k is the constant of proportionality

We are given that at r= 40 the value of t is 50

Substitute the values in 1

Substitute the value of k in 1

Hence equation relating t and r  is and constant of proportionality  is 2000

d. bc = 12 and ef = 16

step-by-step explanation:

we are given that δabc : δdef such that .

also, it is given that

so, from the options, we need that .

a.

b.

c.  

d.

as, we can see that only option d gives the same ratio as i.e. .

hence, the possible lengths are bc = 12 and ef = 16.