HOT Competition (Instagram) 2 Sep/10:00PM: Charlie can eat a large box

Charlie can eat a large box of doughnuts in 4 hours. If Charlie and Milena eat simultaneously at their respective, constant rates, they can finish a large box of doughnuts in 2.5 hours. How many hours would it take Milena to eat the box of doughnuts by herself?

Given

Charlie can complete a task in 4 hours

Charlie and Melina both together can complete a task in 2.5 hours

From above,

As it is given that Charlie complete work in 4 hours we can calculate that Charlie can complete 5/8 of work in 2.5 hours=2.5/4=5/8

So,

Melina so Melina will cover balance 3/8 in 2.5 hours

Which means

Melina can complete the whole work=2.5*8/3=20/3

Answer E

(A) 3/20
(B) 3/2
(C) 20/13
(D) 13/2
(E) 20/3

Posted from my mobile device

Hello guys!

We need to find the time taken by Milena to eat the box by herself,

So, we can say that,
\(\frac{1}{C}\) + \(\frac{1}{M}\) = \(\frac{1}{2.5}\)
We know that \(\frac{1}{C}\)= \(\frac{1}{4}\)
\(\frac{1}{M}\)= \(\frac{1}{2.5} \)- \(\frac{1}{4}\)
\(\frac{1}{M}\)= \(\frac{4}{10}\) - \(\frac{2.5}{10}\)
\(\frac{1}{M}\) = \(\frac{1.5}{10}\)
M= \(\frac{100}{15}\)
M = \(\frac{20}{3}\)

Hence, Melina took 20/3 hours to eat it by herself.

IMO,
Answer:- Option E

Thank you!

Regards,
Raunak Damle

Let’s say entire box of donut is 1

Charlie takes 4 hrs to eat 1
In 1 hr Charlie can eat 1/4
So in 2.5 hrs Charlie eats 2.5/4 = 5/8

So in 2.5 hrs Milena eats 1-5/8 = 3/8

If Milena eats 3/8 in 2.5hrs,
She can eat 1 in 2.5*8/3 hrs = 20/3

Correct answer is E

Posted from my mobile device

Charlie(C) eat a large box of doughnuts in 4 work so C = \(\frac{1}{4}\) work/hours
Charlie(C) and Milena(M) eat the same doughnuts in 2.5 hours so \(\frac{1}{(C+M)}\) = \(\frac{1}{2.5}\) work/hours.

\(\frac{1}{C }\)+ \(\frac{1}{M }\)= \(\frac{1}{(C+M)}\)
\(\frac{1}{4}\)+ \(\frac{1}{M }\) = \(\frac{1}{2.5}\)
\(\frac{1}{M }\) = \(\frac{1}{2.5}\) - \(\frac{1}{4}\)
\(\frac{1}{M }\) = \(\frac{(8-5)}{20}\)
So M = \(\frac{20}{3}\)
I choose E.

Posted from my mobile device

Given

• Charlie can eat a large box of doughnuts in 4 hours.
• Charlie and Milena at their respective, constant rates, can finish a large box of doughnuts in 2.5 hours.

To Find

• The hours would it take Milena to eat the box of doughnuts by herself.

Approach and Working Out

• Charlie can eat in 4 hours.

• Charlie and Milena can eat in 2.5 hours.

• Let’s take LCM of these two as the total quantity.

o 20 units

• Charlie can eat 5 units/hr

• Charlie and Milena 8 units/hr

• Milena = 8 – 5 = 3 units/her.

o Time taken = 20/3 hours

Correct Answer: Option E