The number of masks that Mayerlin kept on her wall given the information in the question is 304.
<h3>What are percentages?</h3>
Percentage is the fraction of an amount that is usually expressed as a number out of hundred. Percentages are a measure of frequency.
<h3>How many masks are on the wall?</h3>
Percentage of the masks on the wall = 100 - 24 = 76%
Number of the masks on the wall = 76% x 400 = 304
To learn more about percentages, please check: brainly.com/question/25764815
We are given the data on the number of candies handed by neighborhood A and neighborhood B.
Let us first find the mean and variance of each neighborhood.
Mean:


Variance:


A. Null hypothesis:
The null hypothesis is that there is no difference in the mean number of candies handed out by neighborhoods A and B.

Research hypothesis:
The research hypothesis is that the mean number of candies handed out by neighborhood A is more than neighborhood B.

Test statistic (t):
The test statistic of a two-sample t-test is given by

Where sp is the pooled standard deviation given by


So, the test statistic is -1.74
Critical t:
Degree of freedom = N1 + N2 - 2 = 6+6-2 = 10
Level of significance = 0.05
The right-tailed critical value for α = 0.05 and df = 10 is found to be 1.81
Critical t = 1.81
We will reject the null hypothesis because the calculated t-value is less than the critical value.
Interpretation:
This means that we do not have enough evidence to conclude that neighborhood A gives out more candies than neighborhood B.
Given:
The ratio is:
1.5 kg : 350 g
To find:
The lowest or simplest form of the given ratio.
Solution:
We know that,
1 kg = 1000 g
We have,
1.5 kg : 350 g
It can be written as





Therefore, the lowest form of the given ratio is 30:7.
The rocket will take a time of approximately 2.686 seconds to hit the ground.
<h3>How much time does a rocket need to hit the ground?</h3>
The height of the rocket (h), in feet, is modelled by a quadratic equation, which is used to model free fall motion, that is, the motion of an object solely due to action of gravity. In this problem we must look for the time when the rocket hits the ground:
- 16 · t² + 40 · t + 8 = 0
(t - 2.686) · (t + 0.186) = 0
Only the first root offers a realistic solution, for time is a non-negative variable. The rocket will take a time of approximately 2.686 seconds to hit the ground.
To learn more on quadratic equations: brainly.com/question/1863222
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