There are 330 different ways for choosing a dozen donuts from the 4 varieties at a donut shop. (at least one donut of every variety must be selected)

<h3>How to calculate the number of ways to select items?</h3>

There are 'r' items from 'n' different varieties (repetition allowed). Then, the number of ways to select items is given by

The number of ways = $_{n+r-1}C_r$

Where the combination $_{n}C_r$ is calculated as

$_{n}C_r=\frac{n!}{r!(n-r)!}$

<h3 /><h3>Calculation:</h3>

It is given that there are 4 varieties of donuts in a shop. I.e., n = 4

Number of donuts to be selected r = 12 (one dozen)

And also given that at least one donut of every variety has to be selected.

Since there are 4 varieties, at least one from each of these means the count is 4.

So, the remaining number of donuts to be selected is 12 - 4 = 8.

So, r becomes 8 i.e., r = 8

On substituting,

the number of ways of selecting the remaining 8 donuts = $_{4+8-1}C_4$

⇒ $_{11}C_4$

⇒ $\frac{11!}{4!(11-4)!}$

⇒ $\frac{11!}{(4!)(7!)}$

⇒ 330

Therefore, there are 330 different ways for choosing a dozen donuts from the 4 varieties at a donut shop.

Learn more about combinations here:

brainly.com/question/11732255

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5 0

2 years ago

find the value of "a" and "b" for which the limit exists both as x approaches 1 and as x approaches 2:

lbvjy [14]

Answer:

a = 4

b = -2

Step-by-step explanation:

If the given function is continuous at x = 1

$\lim_{x \to 1^{-}} f(x)=(x+1)$

$=2$

$\lim_{x \to 1^{+}} f(x)=ax+b$

$=a+b$

$\lim_{x \to 1} f(x)=ax+b$

$=a+b$

And for the continuity of the function at x = 1,

$\lim_{x \to 1^{-}} f(x)=\lim_{x \to 1^{+}} f(x)=\lim_{x \to 1} f(x)$

Therefore, (a + b) = 2 -------(1)

If the function 'f' is continuous at x = 2,

$\lim_{x \to 2^{-}} f(x)=ax+b$

$=2a+b$

$\lim_{x \to 2^{+}} f(x)=3x$

$=6$

$\lim_{x \to 2} f(x)=3x$

$=6$

Therefore, $\lim_{x \to 2^{-}} f(x)=\lim_{x \to 2^{+}} f(x)=\lim_{x \to 2} f(x)$

2a + b = 6 -----(2)

Subtract equation (1) from (2),

(2a + b) - (a + b) = 6 - 2

a = 4

From equation (1),

4 + b = 2

b = -2

3 0

3 years ago