All categories

3 years ago

Please, help me I’m so dumb

Mathematics

1 answer:

Igoryamba3 years ago

7 0

Answer:

Step-by-step explanation:

You know that 9 = 10 - 1.

Then 9 of something is equal to 10 of it less one of it. Here, that "something" is four.

$\begin{array}{cl}9\times4&=10\text{ fours}-\boxed{1}\text{ four}\\&=\boxed{40}-4\\&=\boxed{36}\end{array}$

_____

<em>Comment on this math</em>

This illustrates a shortcut for multiplying by 9 that can be convenient for mental arithmetic. The idea is to multiply by 10, which just involves adding 0 (or moving the decimal point), then subtract the original number.

You might be interested in

Help pls! id appreciate it, trying to get these done tonight

Harlamova29_29 [7]

Is this asking about surface area or volume?

7 0

2 years ago

Read 2 more answers

What is 100 percent of 158

Mashcka [7]

Answer:

It's 63.29

Step-by-step explanation:

Step 1: We make the assumption that 158 is 100% since it is our output value.

Step 2: We next represent the value we seek with x.

Step 3: From step 1, it follows that 100%=158.

Step 4: In the same vein, x%=100.

Step 5: This gives us a pair of simple equations:

100%=158(1).

x%=100(2).

Step 6: By simply dividing equation 1 by equation 2 and taking note of the fact that both the LHS

(left hand side) of both equations have the same unit (%); we have

100%/x% = 158/100

Step 7: Taking the inverse (or reciprocal) of both sides yields

x%/100% = 100/158

x= 63.29%

Therefore, 100 is 63.29% of 158.

4 0

3 years ago

Read 2 more answers

As part of quality-control program, 3 light bulbs from each bath of 100 are tested. In how many ways can this test batch be chos

hichkok12 [17]

Answer:

<h3>By 161700 ways this test batch can be chosen.</h3>

Step-by-step explanation:

We are given that total number of bulbs are = 100.

Number of bulbs are tested = 3.

Please note, when order it not important, we apply combination.

Choosing 3 bulbs out of 100 don't need any specific order.

Therefore, applying combination formula for choosing 3 bulbs out of 100 bulbs.

$^nCr = \frac{n!}{(n-r)!r!}$ read as r out of n.

Plugging n=100 and r=3 in above formula, we get

$^100C3 = \frac{100!}{(100-3)!3!}$

Expanding 100! upto 97!, we get

= $\frac{100\times 99\times 98\times 97!}{97!3!}$

Crossing out common 97! from top and bottom, we get

= $\frac{100\times 99\times 98}{3!}$

Expanding 3!, we get

= $\frac{100\times 99\times 98}{3\times 2\times 1}$

= 100 × 33 × 49

= 161700 ways.

<h3>Therefore, by 161700 ways this test batch can be chosen.</h3>

3 0

3 years ago

What is the answer to -28 + 38

anzhelika [568]

What if I wrote + 38 - 28 .

Would you be able to solve it that way ?

They're both the same number.

6 0

2 years ago

A particular employee arrives at work sometime between 8:00 a.m. and 8:30 a.m. Based on past experience the company has determin

Gala2k [10]

Answer:

0.3333 = 33.33% probability that the employee will arrive between 8:15 a.m. and 8:25 a.m.

Step-by-step explanation:

A distribution is called uniform if each outcome has the same probability of happening.

The uniform distributon has two bounds, a and b, and the probability of finding a value between c and d is given by:

$P(c \leq X \leq d) = \frac{d - c}{b - a}$

A particular employee arrives at work sometime between 8:00 a.m. and 8:30 a.m.

We can consider 8 am = 0, and 8:30 am = 30, so $a = 0, b = 30$

Find the probability that the employee will arrive between 8:15 a.m. and 8:25 a.m.

Between 15 and 25, so:

$P(15 \leq X \leq 25) = \frac{25 - 15}{30 - 0} = 0.3333$

0.3333 = 33.33% probability that the employee will arrive between 8:15 a.m. and 8:25 a.m.

8 0

2 years ago