Class 12th

Parakrima band members are late for a concert in the evening. On their way, they come across a cracked bridge which has no lighting. The bridge is strong enough to hold at most two of them, and they have only one torch with them. Andy can get across the bridge in 2 minutes, Sandy takes 3 minutes, Kandy takes 6 minutes, but Mandy takes 9 minutes. Two band members together can move only as fast as the slower between the two, and one band member must be carrying the torch during the crossing. The band crosses the bridge in such a manner that the total time taken is minimum.

How many ways are there such that all can cross the bridge in min

0 Follower 3 Views

Class 12th Ncert Solutions Maths class 12th

Contributor-Level 10

Following are the possible ways in which Andy, Kandy, Mandy and Sandy can cross the bridge in minimum time.

Case I:

Journey	Men	Time
1 st trip	Andy, Sandy	3 min
Return	Andy, Sandy	2 min
2 nd trip	Kandy, Mandy	9 min
Return	Sandy	3 min
Final trip	Sandy, Andy	3 min
Total time		20 min

Case II:

Journey	Men	Time
1 st trip	Sandy	3 min
Return	Andy, Sandy	3 min
2 nd trip	Kandy, Mandy	9 min
Return	Andy	3 min
Final trip	Sandy, Andy	2 min
Total time		20 min

In total, there are 2 ways to do so.

0 0

New answer posted

8 months ago

A point z moves in the complex plane such that arg $(\frac{z - 2}{z + 2}) = \frac{π}{4},$ then the minimum value of ${| z - 9 \sqrt[]{2} - 2 i |}^{2}$ is equal to________.

0 Follower 2 Views

Raj Pandey

Contributor-Level 9

Let zc be the centre of the circle

$\frac{z_{c} - 2}{z_{c} + 2} = i \Rightarrow z_{c} = 2 i$

Radius of the circle = $\sqrt[]{4 + 4} = 2 \sqrt[]{2}$

Square off minimum distance AB = ${(7 \sqrt[]{2})}^{2} = 98$

0 0

New answer posted

8 months ago

Who are the last two persons to move across the bridge?

0 Follower 1 View

Contributor-Level 10

Sandy and Andy are the last to cross the bridge.

0 0

New answer posted

8 months ago

Directions for questions: Answer the questions on the basis of the information given below.

0 Follower 2 Views

Contributor-Level 10

Two men cross at a time, and one must come back with the torch.

Journey	Men	Time
1 st trip	Andy, Sandy	3 min
Return	Andy, Sandy	2 min / 3
2 and trip	Kandy, Mandy	9 min
Return	Sandy, Andy	3 min / 2
Final trip	Sandy, Andy	3 min

Total time taken for the trip = 20 min

0 0

New answer posted

8 months ago

Class 12th Chemistry

CH₄ is adsorbed on 1g charcoal at 0°C following the Freudlich adsorption isotherm. 10.0 mL of CH₄ is adsorbed at 100 mm of Hg, whereas 15.0 mL is adsorbed at 200 mm of Hg. The volume of CH₄ adsorbed at 300 mm of Hg is 10^x mL. The value of x is ______* 10^-2.

(Nearest integer)

[Use log₁₀ 2 = 0.3010, log₁₀3 = 0.4771]

0 Follower 2 Views

Vishal Baghel

Contributor-Level 10

$(\frac{x}{m}) = K P^{1 / n}$

$\frac{10}{1} = K {(100)}^{1 / n} . . . . . . . . . . . . . . . . (1)$

$\frac{15}{1} = K {(200)}^{1 / n} . . . . . . . . . . . . . . . . (2)$

$\frac{V}{1} = K {(300)}^{1 / n} . . . . . . . . . . . . . . . (3)$

Dividing (2) by (1)

$\frac{15}{10} = {(\frac{2}{1})}^{1 / n}$ = (2)^1/n

$\frac{V}{10} = 1 0^{0.279}$

$V = 10 * 1 0^{0.279} = 1 0^{1.279} = 1 0^{x}$

$∴ x = 1.279 = 127.91 * 1 0^{- 2} \approx 128 * 1 0^{- 2}$

Ans. = 128

0 0

New answer posted

8 months ago

Answer the questions on the basis of the information given below.

In a school when a survey is conducted on liking of subjects out of three subjects physics, chemistry mathematics then outcome is as follow.

Total number of students who like physics, chemistry and mathematics is 30, 40, 50 respectively. 10 students shown interest in all three subjects, Number of students who like physics and mathematics both is equal to number of students who like chemistry and mathematics both and is equal to 3/4 times number of students who like physics and chemistry both 15 students like only chemistry.

When class teacher saw this survey report he to

0 Follower 2 Views

alok kumar singh

Contributor-Level 10

From the given condition g = 10,

Number of students who like both Physics and Maths = 10 + f

Number of students who like both chemistry and Maths = 10 + e

From given condition 10 + f = 10 + e or e = f

Similarly from 3^rd condition ¾ (10 + e) = 10 + d

Or 30 + 3e = 40 + 4d

Since 15 students like only chemistry hence b = 15

Number of students who like only chemistry is 40

Hence e + g + d + b = 40

or e + 10 + (3e – 10)/4 + 15 = 40

or (7e – 10)/4 = 15 or 7e = 70 or e = 10

Hence a = 5, c = 20, f = e = 10, d = 5

Hence the distribution is as follows

As per the observation of class teacher actual numbers of students who like Physics in

...more

0 0

New answer posted

8 months ago

Class 12th Chemistry

The transformation occurring in Duma's method is given below:

$C_{2} H_{7} N + (2 x + \frac{y}{2}) C u O \to x C O_{2} + \frac{y}{2} H_{2} O + \frac{z}{2} N_{2} + (2 x + \frac{y}{2}) C u$

The value of y is________. (Integer answer)

0 Follower 6 Views

Vishal Baghel

Contributor-Level 10

$C_{2} H_{7} N + (2 x + \frac{y}{2}) C u O \to x C O_{2} + \frac{y}{2} H_{2} O + \frac{Z}{2} N_{2} + (2 x + \frac{y}{2}) C u$

$C_{2} H_{7} N_{1} + (2 * 2 + \frac{7}{2}) C u O \to 2 C O_{2} + \frac{7}{2} H_{2} O + \frac{1}{2} N_{2} + (2 * 2 + \frac{7}{2}) C u$

$∴ y = 7$

Ans. = 7

0 0

New answer posted

8 months ago

Class 12th Physics

A uniform heating wire of resistance 36 $Ω$ is connected across a potential difference of 240V. The wire is then cut into half and a potential difference of 240 V is applied across each half separately. The ratio of power dissipation in first case to the total power dissipation in the second case would be 1 : x, where x is________.

0 Follower 3 Views

alok kumar singh

Contributor-Level 10

In first condition R₁ = 36 $Ω$

In second condition R₂ = 18 $Ω$

$P_{1} = \frac{V^{2}}{R_{1}} = \frac{{(240)}^{2}}{36}$

$P_{2} = \frac{V^{2}}{R_{2}} + \frac{V^{2}}{R_{2}} = \frac{{(240)}^{2}}{18} + \frac{{(240)}^{2}}{18}$

$P_{2} = \frac{{(240)}^{2}}{9}$

So $\frac{P_{1}}{P_{2}} = \frac{{(240)}^{2} / 36}{{(240)}^{2} / 9} = \frac{1}{4}$

x = 4

0 0

New answer posted

8 months ago

Class 12th Maths

The square of the distance of the point of intersection of the line $\frac{x - 1}{2} = \frac{y - 2}{3} = \frac{z + 1}{6}$ and the

plane 2x – y + z = 6 from the point (-1, -1, 2) is________.

0 Follower 6 Views

Raj Pandey

Contributor-Level 9

$? \frac{x - 1}{2} = \frac{y - 2}{3} = \frac{z + 1}{6} = r (s a y)$

Let P (1 + 2r, 2 + 3r, 1 + 6r) lies on the plane 2x – y + z = 6

$∴ r = 1 \Rightarrow P (3, 5, 5)$

Distance between P and Q is PQ = $\sqrt[]{16 + 36 + 9} = \sqrt[]{61}$

$∴ P Q^{2} = 61$

0 0

New answer posted

8 months ago

There were ten events in the last years “annual sports meet” of XYZ international school. Following guidelines have been issued to schedule the “annual sports meet”:

I. A school board has organized the meet for ten events Cultural fest, Science exhibition, Writing , Reading, Dress, Quiz , Festivals, Planting, Drawing and Picnic on six days of week with holiday on Sunday; not having more than two events on any of the days.

II. Event begins on Wednesday with event Quiz .

III. Reading is accompanied by some other event but not on Thursday. Cultural fest and Festivals

are on the same day immediately after the holiday.

IV. The

0 Follower 3 Views