Mary wrote a book of 1536 pages. She numbered all pages by hand. How many times did she write the digit 6?

A King in ancient times agreed to reward the inventor of chess with one grain of wheat on the first of the 64 squares of a chess

statuscvo [17]

Let's start by visualising this concept.

Number of grains on square:
1 2 4 8 16 ...

We can see that it starts to form a geometric sequence, with the common ratio being 2.

For the first question, we simply want the fifteenth term, so we just use the nth term geometric form:
$T_n = ar^{n - 1}$
$T_{15} = 2^{14} = 16384$

Thus, there are 16, 384 grains on the fifteenth square.

The second question begs the same process, only this time, it's a summation. Using our sum to n terms of geometric sequence, we get:
$S_n = \frac{a(r^{n} - 1)}{r - 1}$
$S_{15} = \frac{2^{15} - 1}{2 - 1}$
$S_{15} = 2^{15} - 1 = 32767$

Thus, there are 32, 767 total grains on the first 15 squares, and you should be able to work the rest from here.

6 0

2 years ago

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Deon plans to ride a 15-mi bicycle trail. If his average speed is 20 mi/h, which equation can he use to find the time t, in hour

fredd [130]

Answer:

The equation that Deon can use to find the time 't' it takes for his ride is t=distance/rate or t=15/20 or 0.75 hours.

Step-by-step explanation:

The relationship between distance, rate and time is a common formula represented by d=rt where 'd'=distance, 'r'=rate and 't'=time. Distance is typically calculated in miles, where rate is given in miles/hour and time is the hours. In this case, because we are looking for 't', we would simply plug in the values of distance and rate to get 20=15t. In order to solve for 't', we need to use inverse (opposite) operations, dividing both sides by 15 and getting 0.75 hours for 't'.

8 0

2 years ago

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Jacinta buys 4 pounds of turkey and 2 pounds of ham. She pays a total of $30, and the turkey costs $1.50 less per pound than the

marissa [1.9K]

Given

jacinta buys 4 pounds of turkey and 2 pounds of ham & pays a total of $30, turkey costs $1.50 less per pound than the ham.

find out the combined cost of 1 pound of turkey and 1 pound of ham

To proof

As given in the question

jacinta buys 4 pounds of turkey and 2 pounds of ham

total pay by jacinta = $30

let us assume that the price of the ham = x

as given in the question

turkey costs $1.50 less per pound than the ham

turkey costs becomes = x - 1.50

then the equation becomes

30 = 4 (x - 1.50) + 2x

30 = 4x + 2x - 6

36 = 6x

x = 6

thus

ham cost per pound = $6

turkey cost per pound = 6 - 1.50

= $ 4.5

Now find out

cost of 1 pound of turkey + 1 pound of ham = $ 6 + $ 4.5

= $ 10.5

Hence proved

5 0

2 years ago

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Rectangle lmno is rotated 90 degrees clockwise around the origin to create l’m’n’o which statement best describes the relationsh

vova2212 [387]

Answer:

The correct option is A: they are equidistant from origin

Step-by-step explanation:

Since the rotation is performed around the fixed axis on its origin, there will not be any change to the distances between the origin and the point n or n'. The size of the rectangle has neither increased or decreased so, it cannot be possible that the distance between the origin and the point n could change after the object is rotated.

Hope that answers the question, have a great day!

4 0

2 years ago

Direct Mailing Company sells computers and computer parts by mail. The company claims that more than 90% of all orders are maile

lys-0071 [83]

Answer:

We conclude that less than or equal to 90% of all orders are mailed within 72 hours after they are received which means the company's claim is not true.

Step-by-step explanation:

We are given that the company claims that more than 90% of all orders are mailed within 72 hours after they are received. The quality control department at the company often takes samples to check if this claim is valid.

A recently taken sample of 175 orders showed that 161 of them were mailed within 72 hours.

Let p = percentage of all orders that are mailed within 72 hours.

SO, Null Hypothesis, $H_0$ : p $\leq$ 90% {means that less than or equal to 90% of all orders are mailed within 72 hours after they are received}

Alternate Hypothesis, $H_A$ : p > 90% {means that more than 90% of all orders are mailed within 72 hours after they are received}

The test statistics that will be used here is One-sample z proportion statistics;

T.S. = $\frac{\hat p-p}{{\sqrt{\frac{\hat p(1-\hat p)}{n} } } } }$ ~ N(0,1)

where, $\hat p$ = proportion of orders that were mailed within 72 hours in a sample of 175 = $\frac{161}{175}\times 100$ = 92%

n = sample of orders = 175

So, test statistics = $\frac{0.92-0.90}{{\sqrt{\frac{0.92(1-0.92)}{175} } } } }$

= 0.975

The value of the test statistics is 0.975.

Now at 1% significance level, the z table gives critical value of 2.3263 for right-tailed test. Since our test statistics is less than the critical value of z as 0.975 < 2.3263, so we have insufficient evidence to reject our null hypothesis as it will not fall in the rejection region due to which we fail to reject our null hypothesis.

Therefore, we conclude that less than or equal to 90% of all orders are mailed within 72 hours after they are received which means the company's claim is not true.

6 0

2 years ago