Question

Бабушка и внучка лепят пельмени.Бабушка может слепить 420 пельменей за час,а внучка- пока только 120 штук.За какое время они слепят 180 пельменей работая вместе

Answer 1

Вместе в час они лепят 420+120=540 пельменей
180/540= 1/3 часа=20 минут

Answer 2

Problem Analysis

We are given that a grandmother can make 420 dumplings in an hour, while her granddaughter can only make 120 dumplings. We need to determine how long it will take for them to make 180 dumplings if they work together.

Solution

To solve this problem, we can calculate the combined rate at which the grandmother and granddaughter make dumplings and then use that rate to find the time it takes to make 180 dumplings.

Let's denote the time it takes for them to make 180 dumplings together as t.

The rate at which the grandmother makes dumplings is 420 dumplings per hour, so her rate is 420 dumplings per hour.

The rate at which the granddaughter makes dumplings is 120 dumplings per hour, so her rate is 120 dumplings per hour.

To find the combined rate, we add their individual rates:

Combined rate = Grandmother's rate + Granddaughter's rate

Let's substitute the values:

Combined rate = 420 dumplings per hour + 120 dumplings per hour

Now, we can calculate the combined rate:

Combined rate = 540 dumplings per hour

Since we know the combined rate and we want to find the time it takes to make 180 dumplings, we can use the formula:

Time = Amount / Rate

Substituting the values:

t = 180 dumplings / 540 dumplings per hour

Simplifying:

t = 1/3 hour

Therefore, it will take them 1/3 hour to make 180 dumplings if they work together.

Answer

If the grandmother and granddaughter work together, it will take them 1/3 hour to make 180 dumplings.

Note: The answer is based on the given information and calculations.