4. The time taken for passengers to be checked-in for a flight is inversely proportional to the number of staff working. It takes 30 minutes for passengers to be checked-in
when 5 staff are working. How long will it take if 15 staff are working?​

90minutes

Step-by-step explanation:

Let the time taken for passengers to be checked-in be t

Let the number of staff working be w;.

If the time taken for passengers to be checked-in for a flight is inversely proportional to the number of staff working then;

t = kw

when t = 30, w = 5

30 = 5k

k = 30/5

k = 6

to get t when w = 15

t = kw

t = 6(15)

t = 90minutes

Hence it will take 90minutes long

it would be:

c.parallelogram.