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3 years ago

How do I change my level? It says I am in high school but I am only in middle school.

Mathematics

1 answer:

weqwewe [10]3 years ago

5 0

Answer:

go on your profile ---> edit profile----> preferences

Step-by-step explanation:

You might be interested in

Leah has two savings accounts with balances totaling $8,000. She withdrew 15% from one and

DedPeter [7]

Answer:930 Hope this Helps :D

Step-by-step explanation:

For the given problem:

Let the balances of the saving accounts be (x) and (y)

Leah has two savings accounts with balances totaling $8,000

so,

x+y=8000 (1)

She withdrew 15% from one and 40% from the other. If she has $6,350 remaining in the accounts

So, The remaining from the accounts will be (1 - 15%) and ( 1 - 40%)

that will give the decimals: 0.85 and 0.6

so, we can write the following equation:

0.85x+0.6y=6350 (2)

Now, solve the equations (1) and (2) to find (x) and (y)

From equation (1)

y=8000-x (3)

Substitute with (y) from equation (3) into equation (2)

0.85x+0.6*(8000)-x =6350

Now solve the equation

0.85x+0.6*8000-0.6x=6350

0.85x-0.6+4800+6350

0.25x=6350-4800

0.25x=1550

x=6200

Substitute with (x) into equation (3) to find (y)

y=8000-6200=1800

So, the larger account = x = 6200

and the smaller account = y = 1800

Now, we will answer the question, how much money did she withdraw from the account with the larger balance?

so, the answer will be: 15% of x = 0.15 * 6200 = 930

So, the answer will be $930

6 0

2 years ago

A math professor notices that scores from a recent exam are normally distributed with a mean of 61 and a standard deviation of 8

Alexeev081 [22]

Answer:

a) 25% of the students exam scores fall below 55.6.

b) The minimum score for an A is 84.68.

Step-by-step explanation:

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

Mean of 61 and a standard deviation of 8.

This means that $\mu = 61, \sigma = 8$

(a) What score do 25% of the students exam scores fall below?

Below the 25th percentile, which is X when Z has a p-value of 0.25, that is, X when Z = -0.675.

$Z = \frac{X - \mu}{\sigma}$

$-0.675 = \frac{X - 61}{8}$

$X - 61 = -0.675*8$

$X = 55.6$

25% of the students exam scores fall below 55.6.

(b) Suppose the professor decides to grade on a curve. If the professor wants 0.15% of the students to get an A, what is the minimum score for an A?

This is the 100 - 0.15 = 99.85th percentile, which is X when Z has a p-value of 0.9985. So X when Z = 2.96.

$Z = \frac{X - \mu}{\sigma}$

$2.96 = \frac{X - 61}{8}$