You are buying a mobile phone and look at the table of tariffs below. Network - TalkLots Texts Minutes Charge per month
Contract 500 100 £15.00
Pay as You Go 10p each 20p a minute None

How much would you pay if you sent 50 texts and used 65 minutes on the “Pay as You Go” package with TalkLots?

£

If you sent 40 texts a month and used 50 minutes, would you be better to go onto a contract with TalkLots?

Aspacecraft can attain a stable orbit 300 kilometers above earth if it reaches a velocity of 7.7 kilometers per second. the formula for a rocket's maximum velocity v in kilometers per second is vequalsminus0.0098tplusc ln upper r, where t is the firing time in seconds, c is the velocity of the exhaust in kilometers per second, and r is the ratio of the mass of the rocket filled with fuel to the mass of the rocket without fuel. find the velocity of a spacecraft whose booster rocket has a mass ratio of 20, an exhaust velocity of 2.1 km/s, and a firing time of 15 s. can the spacecraft achieve a stable orbit 300 km above earth?