Question

EXAMPLE-5 A train has a speed of 60 km/h for the first one hour and 40 km/h for the next half an hour. Its average speed in km/h is (JIPMER 1999] (a) 50 (b) 53.33 (c) 48 (d) 70​

Answer 1

Explanation:

please mark as BRAINEST

Answer 2

⇝Given :-

• Speed of 60 km/h in first 1 hour.
• Speed of 40 km/h in next half hour.

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⇝To Find :-

• Find the average speed.

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⇝Formula Used :-

➵Distance :

${\large{\bigstar{\underline{\boxed{\red{\bf{\pmb{Distance = Speed \times Time}}}}}}}}{\bigstar}$

➵Average Speed :

${\large{\bigstar{\underline{\boxed{\red{\bf{\pmb{Average \: Speed = \frac{total \: distance}{total \: time} }}}}}}}}{\bigstar}$

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⇝Solution :-

❒ First finding Distance :

${\orange{✥{\underline{\purple{\bf{For \: first \: 1 \: hour \: }}}}}}$

${\large{:{\longmapsto{\bf{Distance = Speed \times Time}}}}}$

${\large{:{\longmapsto{\bf{Distance = 60 \times 1}}}}}$

${\large{\pink{:{\longmapsto{\underline{\overline{\boxed{\bf{ Distance(1) = 60 km}}}}}}}}}$

${\orange{✥{\underline{\purple{\bf{For \: next \: half \: hour \: }}}}}}$

${\large{:{\longmapsto{\bf{Distance = Speed \times Time}}}}}$

${\large{:{\longmapsto{\bf{Distance = 40 \times 0.5}}}}}$

${\large{\pink{:{\longmapsto{\underline{\overline{\boxed{\bf{ Distance(2) = 20 km}}}}}}}}}$

❒ Now Average Speed :

${\large{\dashrightarrow{\bf{Average \: Speed = \frac{total \: distance}{total \: time} }}}}$

${\large\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: {\dashrightarrow{\bf{ \frac{60 + 20}{1 + 0.5} }}}}$

${\large\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: {\dashrightarrow{\bf{ \frac{80}{1.5} }}}}$

${\large\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: {\dashrightarrow{\bf{ {\cancel\frac{80}{1.5} }}}}}$

${\large{\red{\pmb{\boxed{\underline{\overline{\bf{Average Speed =53.33km /h}}}}}}}}$

❒ Hence :

➻ (B.) option is correct .

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