Question

solve it fast... ?!!​

Answer 1

$\sf{\bold{\green{\underline{\underline{Given}}}}}$

Total time = 10 hrs

Speed for 1st 3 hrs = 60 km/h

Speed for 2nd 7 hrs = 40km/h

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$\sf{\bold{\green{\underline{\underline{To\:Find}}}}}$

average speed = ???

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$\sf{\bold{\green{\underline{\underline{Solution}}}}}$

★$\sf{\red{{\boxed{\mathsf{ 1st \: CASE }}}}}$

⠀⠀⠀⠀

$\sf{\pink{\boxed{\bold{Speed =\dfrac{distance}{time}}}}}$

⠀⠀⠀⠀

: $\sf\implies \: {\bold{ 60 = \dfrac{distance}{3}}}$

⠀⠀

: $\sf\implies \: {\bold { distance = 60 \times 3 }}$

⠀⠀

: $\sf\implies \: {\bold { distance = 180km}}$

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$\sf{\orange{\boxed{\bold{distance = 180km }}}}$

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★$\sf{\red{{\boxed{\mathsf{ 2nd \: CASE }}}}}$

⠀⠀⠀⠀

$\sf{\pink{\boxed{\bold{Speed =\dfrac{distance}{time}}}}}$

⠀⠀⠀⠀

: $\sf\implies \: {\bold{ 40 = \dfrac{distance}{7}}}$

⠀⠀

: $\sf\implies \: {\bold { distance = 40 \times 7 }}$

⠀⠀

: $\sf\implies \: {\bold { distance = 280km}}$

⠀⠀⠀⠀

$\sf{\orange{\boxed{\bold{distance = 280km }}}}$

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$\sf{\pink{\boxed{\bold{average \: speed = \dfrac{total\: distance}{total\: time \: taken }}}}}$

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: $\sf\longrightarrow \: {\bold{ average \: speed = \dfrac{ 180 + 280 }{ 7 + 3 }}}$

⠀⠀

: $\sf\longrightarrow \: {\bold{ average \: speed = \dfrac{ 460 }{ 10 }}}$

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: $\sf\longrightarrow \: {\bold{ average \: speed = 46km/h }}$

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$\sf{\orange{\boxed{\bold{ average \: speed = \: 46km/h }}}}$

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$\sf{\bold{\green{\underline{\underline{Answer}}}}}$

Average speed = 46 km / h

46 km / h = option B

Answer 2

Given :-

• Speed for 1st 3 hrs is 60 km/h
• Speed for 2nd 7 hrs = 40km/h
• Time Taken = 10 hours

To Find :-

• What is the average speed of car during the journey ?

Solution :-

In first condition

Applying the formula of speed .

⠀⠀⠀⠀

$\sf{{\boxed{\bold{Speed =\dfrac{Distance}{time}}}}}$

⇒ 60 ↠ Distance / 3

⇒ Distance ↠ 60 × 3

⇒ Distance ↠ 180km

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Now , In 2nd Condition ⠀⠀⠀⠀

Again applying,

$\sf{{\boxed{\bold{Speed =\dfrac{Distance}{time}}}}}$

⠀⠀⠀⠀

⇒ 40 ↠Distance / 7

⇒ Distance ↠ 40 × 7

⇒ Distance ↠ 280km

⠀⠀⠀⠀

$\sf{{\boxed{\bold{Average \: speed=\dfrac{Total \: distance}{Total\: time}}}}}$

Average speed = { 180 + 280 } / { 7 + 3 }

⠀⠀

$\longmapsto\tt{A=\cancel\dfrac{460}{10}}$

Average speed ↠ 46km/hr

Therefore ,

➤ The average speed of car during the journey is 46 km/hr.

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