Question

A watch which gains 6 seconds in 2 minutes was set right at 7 am. On the same day, when the watch indicated 10:30 am, the true time is

Answer 1

Answer:

10:20am

Step-by-step explanation:

Error is 6 secs for 2 mins

or 3 secs for 1 mins

or 3 secs for 60 secs

or 1/20 secs for every

secs.

The time difference as per the faulty watch is 3hr:30 mins

or 210 mins

or 12600 secs

If the actual time is x secs,then the relationship between actual time and incorrect time is

$x + \frac{x}{20} = 12600$

$21x = 12600 \times 20$

$x = 12000$

Hence actual time lapse is 12000 secs

or 200 mins

or 3 Hr:20 mins

Hence time is 10:20am

Answer 2

Answer:

true time as 9a.m.28min .

Step-by-step explanation:

Given :- Problem statement :

• watch gains 6 sec in 2 min
• set time is 7 a.m.

To find :- true time , when watch is at 10:30 am

Solution :-

Step 1) Watch gains 6 sec in 2 min ;

then ,  2 min.6sec = 2min + 0.1 min = 2.01 min ---  (1)  { since 1 min = 60 sec , thus 6 sec = 0.1 min }

Step 2) From 7 a.m. till 10:30 a.m. = 2hr.30 min = 210 min --- (2)

Step 3) 2.01 min = 2 min ,

then 210 min = x (let say )

By applying ratio and proportion concept ,

x = 208.955 min

x = 208.955 / 60 = 3.48 hrs .

Step 4) 3.48 hrs = 3 hr + 0.48 hr

Step 5) 0.48 hrs = 28.8 min

Hence time taken is 2hr . 28.8min

i.e. True time is from 7 a.m. 2hr.28.8min ,

we get true time as 9a.m.28min

#SPJ3