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Elina [12.6K]
3 years ago
14

A boy is building a pyramid out of building blocks. He puts 20 blocks in the first row, then he puts 19 blocks in the row above,

and so on. Find the total number of blocks he needs.
Mathematics
1 answer:
rjkz [21]3 years ago
8 0

Answer:

<h3>The answer is 206 I believe</h3>

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A certain test preparation course is designed to help students improve their scores on the LSAT exam. A mock exam is given at th
OlgaM077 [116]

Answer:

Interval [16.34 , 21.43]

Step-by-step explanation:

First step. <u>Calculate the mean</u>

\bar X=\frac{(23+18+23+12+13+23)}{6}=18.666

Second step. <u>Calculate the standard deviation</u>

\sigma =\sqrt{\frac{(23-18.666)^2+(18-18.666)^2+(23-18.666)^2+(12-18.666)^2+(13-18.666)^2+(23-18.666)^2}{6}}

\sigma=\sqrt\frac{18.783+0.443+18.783+44.435+5.666+18.783}{6}

\sigma=\sqrt{17.815}=4.22

As the number of data is less than 30, we must use the t-table to find the interval of confidence.

We have 6 observations, our level of confidence DF is then 6-1=5 and we want our area A to be 80% (0.08).  

We must then choose t = 1.476 (see attachment)

Now, we use the formula that gives us the end points of the required interval

\bar X \pm t\frac{\sigma}{\sqrt n}

where n is the number of observations.

The extremes of the interval are then, rounded to the nearest hundreth, 16.34 and 21.43

6 0
3 years ago
Each second for 4 seconds, an elevator descends 10 feet. Find the total change in elevation.
NISA [10]
(4 sec) * (-10 ft/sec) = -40 ft.
5 0
3 years ago
Here are two closed containers and four balls just fit into each container. Each ball has a diameter of 60mm. Which container ha
Studentka2010 [4]

Answer:

Container B has smaller surface area.

Step-by-step explanation:

Given:

Container A

Radius = 60/2 = 30 mm

Height = 4 x 60 = 240 mm

Container B

Length = 120

Width = 120

Height = 60

Computation:

Surface area of container A (Cylinder) = 2πr[h+r]

Surface area of container A (Cylinder) = 2[22/7][60][120+60]

Surface area of container A (Cylinder) = 67,885.70 mm² (Approx)

Surface area of container B (Cuboid) = 2[lb+bh+hl]

Surface area of container B (Cuboid) = 2[(14,400)+(7,200)+(7,200)]

Surface area of container B (Cuboid) = 57,600 mm²

Container B has smaller surface area.

8 0
3 years ago
What is the product of (BY*)(274)
gulaghasi [49]

Answer:

i

Step-by-step explanation:

8 0
2 years ago
How many days was she away
SSSSS [86.1K]
The answer will be 17
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