Question

A mobile company charges Rs. 1.50 per minute during the daytime i.e. from 7.00 am to 11.00 pm and Rs. 'x' per minute during the night i.e. from 11.00 pm to 7.00 am. The total talking
time per hour decreases by 50% during the night. Find the value of 'x' if the average amount
charged by the mobile company during the whole day is Rs. 1.40 per minute.​

Answer 1

Answer: 1 per minute during night

using combined average formula

$\frac{N1*X1+N2*X2}{N1+N2} = X(C)$

Ps here x is used as mean symbol

Step-by-step explanation:

Using combined average

rate x hours x talk time (min)

1.5 x 1.6 x 1(suppose)

for day time

for night time

rate x hours x talk time (min)

(as decrease by 50%)

$\frac{1.5 * 1.6 * 1+x * 8 * 0.5}{16+(8*0.5)} = 1.4$

simplify to get x=1