Workings please......

A wheel on Aldo's bicycle is 1.1 ft in diameter. Aldo races the bicycle for 110 ft . How many times does the wheel turn as the b

Svetllana [295]

Circumference = PI x Diameter

circumference of tire = 3.14 x 1.1 = 3.454 feet

so every full turn of the tire the bike travels 3.454 feet

110 feet / 3.454 = 31.8 turns

3 0

3 years ago

An online data base charges $25 an hour during the day and $12.50 an hour at night. If a research company paid $250 for 12 hours

Firdavs [7]

Answer

Find out the which system of equations could be used to determine the number of hours charged at the day rate (d) and at the night rate (n) .

To proof

As given in the question

Let us assume that the number of hours charged at the day rate = d

Let us assume that the number of hours charged at the night rate = n

An online data base charges $25 an hour during the day and $12.50 an hour at night. If a research company paid $250 for 12 hours of use.

Total working hour in a company including day and night be 12 hours .

than the equation become in the form

d + n = 12

also

An online data base charges $25 an hour during the day

$12.50 an hour at night.

If a research company paid $250 for 12 hours of use.

than the equation becomes

25d + 12.50n = 250

than the two equation are

d + n = 12 , 25d + 12.50n = 250

multiply first by 25 and subtracted from 25d + 12.50n = 250

25d - 25d + 12.50n - 25n = 250 - 300

12.5 n = 50

$n = \frac{50}{12.5}$

n = 4hours

put this in the d + n = 12

d + 4 =12

d = 12-4

d = 8 hours

Therefore the number of hours charged at the day rate is 8 hours and at the night rate is 4hours .

Hence proved

4 0

3 years ago

Two lighthouses are located 75 miles from one another on a north-south line. If a boat is spotted S 40o E from the northern ligh

yuradex [85]

Answer:

The northern lighthouse is approximately $24.4\; \rm mi$ closer to the boat than the southern lighthouse.

Step-by-step explanation:

Refer to the diagram attached. Denote the northern lighthouse as $\rm N$ , the southern lighthouse as $\rm S$ , and the boat as $\rm B$ . These three points would form a triangle.

It is given that two of the angles of this triangle measure $40^{\circ}$ (northern lighthouse, $\angle {\rm N}$ ) and $21^{\circ}$ (southern lighthouse $\angle {\rm S}$ ), respectively. The three angles of any triangle add up to $180^{\circ}$ . Therefore, the third angle of this triangle would measure $180^{\circ} - (40^{\circ} + 21^{\circ}) = 119^{\circ}$ (boat $\angle {\rm B}$ .)

It is also given that the length between the two lighthouses (length of $\rm NS$ ) is $75\; \rm mi$ .

By the law of sine, the length of a side in a given triangle would be proportional to the angle opposite to that side. For example, in the triangle in this question, $\angle {\rm B}$ is opposite to side $\rm NS$ , whereas $\angle {\rm S}$ is opposite to side ${\rm NB}$ . Therefore:

$\begin{aligned} \frac{\text{length of NS}}{\sin(\angle {\rm B})} = \frac{\text{length of NB}}{\sin(\angle {\rm S})} \end{aligned}$ .

Substitute in the known measurements:

$\begin{aligned} \frac{75\; \rm mi}{\sin(119^{\circ})} = \frac{\text{length of NB}}{\sin(21^{\circ})} \end{aligned}$ .

Rearrange and solve for the length of $\rm NB$ :

$\begin{aligned} & \text{length of NB} \\ =\; & (75\; \rm mi) \times \frac{\sin(21^{\circ})}{\sin(119^{\circ})} \\ \approx\; & 30.73\; \rm mi\end{aligned}$ .

(Round to at least one more decimal places than the values in the choices.)

Likewise, with $\angle {\rm N}$ is opposite to side ${\rm SB}$ , the following would also hold:

$\begin{aligned} \frac{\text{length of NS}}{\sin(\angle {\rm B})} = \frac{\text{length of SB}}{\sin(\angle {\rm N})} \end{aligned}$ .

$\begin{aligned} \frac{75\; \rm mi}{\sin(119^{\circ})} = \frac{\text{length of SB}}{\sin(40^{\circ})} \end{aligned}$ .

$\begin{aligned} & \text{length of SB} \\ =\; & (75\; \rm mi) \times \frac{\sin(40^{\circ})}{\sin(119^{\circ})} \\ \approx\; & 55.12\; \rm mi\end{aligned}$ .

In other words, the distance between the northern lighthouse and the boat is approximately $30.73\; \rm mi$ , whereas the distance between the southern lighthouse and the boat is approximately $55.12\; \rm mi$ . Hence the conclusion.