Joey is going crazy!

She saw a car drive up and suddenly brake suddenly! Suddenly rushed out a few people! Suddenly picked up a black cloth bag and covered Lu Weiwei's head and face! Then tow it into the car!

Everything happened so fast, in just a few seconds, the car was already far away!

The people in the vicinity who saw this scene were shocked, and no one dared to believe that such a thing could happen at the school gate in broad daylight.

"What to do? …… What to do?! Yes, call the police! I'm going to call the police! ......" Joey was so anxious that she burst into tears, and took out her mobile phone to call the police in a panic, "...... Why can't I get through?! ”

A well-wisher next to her reminded her: "The school has installed a signal jammer, you have to stay away to use your mobile phone." ”

Signal jammers can block cell phone signals, and many schools have such devices, which are mainly used in exam rooms to prevent students from cheating on exams.

However, Lanyang School has been using blockers for a long time, not only to prevent cheating, but also to prevent students from playing with mobile phones and not studying.

Joey didn't have time to think about why the school was so strict, she ran desperately forward with her mobile phone, panicked, stumbled, and looked at her cell phone signal as she ran!

I finally ran to the place where there was a signal, got through the alarm number, transferred the headquarters to the branch, and the branch to the region, and finally explained the situation to the operator!

The other party asked her: "Do you remember what the license plate number is?" ”

"The license plate number is...... It's ......" Joey's mind was full of chaos, "It's Q3...... No, Q6? ……”

The tears fell more urgently, and she couldn't remember!

“Q8103F。” Zhen Zhu said on the side.

"It's Q8103F!" Joey immediately said to the other side of the phone.

"Okay, the police will be there soon, please wait where you are, don't leave ......"

"You must be quick! Be sure to stop that car! Joey cried.

After hanging up the phone, Qiao Yiqi stood on the side of the road, anxiously looking at both sides, wishing that he could not immediately see the police car appear in front of him!

But I waited a long time.

Maybe it's three or five minutes, maybe a quarter of an hour, she has no idea about time now, she just feels that every minute and every second is incomparably long!

Joey was anxious.

The mobile phone rang suddenly, it was an unfamiliar number, and Joey answered the phone.

"I'm Lin Chen." The man's voice on the other end of the phone was unusually calm, "I already know the slight situation, the police are trying to find a way to intercept the car, considering that the other party may be driving a fake license vehicle, so I need you to provide the model and color, do you remember?" ”

Lin Chen couldn't panic.

Once he panics, the people he asks will only panic even more!

"Remember!" Joey hurriedly said, "It's a gray SUV!" ”

"Do you remember the exact time it happened?" Lin Chen asked.

By calculating the radius of movement of the car over time, it is possible to intercept and search more efficiently.

Qiao Yi froze when she heard this.

All she knew was that it was around 5 o'clock.

4:50 and 5:10 fall into this category, and the length of nearly 20 minutes is enough for a car to run twenty or thirty kilometers!

What if the alarm time prevails? …… It's not accurate, because she doesn't remember how long it took her to find a signal!

"Remember?" Lin Chen asked again, "The phone record shows that it was 5:09, how long has it been since this time when the accident happened?" One minute? Three minutes, or more? ”

Joey was dumbfounded.

Vehicles drove by in front of me, fast and slow. Cold sweat broke out on her back.

If you get the time wrong, even if it's just 1 minute, it can delay the rescue!

"5:06." Zhen Zhu, who was beside her, said suddenly.

Qiao Yi looked at Zhen Zhu suspiciously, "Do you remember the time?" ”

Zhen Zhu pointed to the bus stop not far away, "There are 4 buses here, the departure interval of each bus is 30 minutes, just took a bus when the accident happened, and now it has passed again, set the initial time to 0, and use the cumulative density function to find the waiting time in the middle,

P(Xminx)=1-(1-x\/30)4，

The derivative gives the probability density function of Xmin...... Then use the integral to obtain,

E(Xmin)=∫30\/0x·p(x)dx=6，

It's 5:12 a.m., minus the average wait time of 6, and the incident time is 5:06 a.m. ”